Alright, so starting with Daoism, a Chinese philosophical tradition which encourages adherence to the Dao (The Way), in order to achieve perfection. In order to do this, one must recognise and be cognizant of the universe's fundamental nature, the theory of creationism under Daoism. This is represented through Wuji (Nothingness / 'Without Ridgepole'), which is the first and foremost component of that theory. Wuji as a concept encompasses nothingness before creation, the void prior to the emergence of all that exists.
From this, Wuji, comes Taiji (Supreme Ultimate / 'Great Ridgepole'). It is all of existence which emerges from nothingness, a similar 'blanket' concept to Wuji. Fundamental to all things in existence, Taiji, is Yin and Yang. They naturally emerge alongside the Taiji because they are inherent to everything that exists. Yin and Yang are intrinsically connected, one cannot exist in the absence of the other. The best account I can give of their relationship is that of night and day. Yin, representing the darkness, the night, can only occur because Yang, representing the light, the day, flows into it as time itself too flows. Likewise, Yang can only exist once the night flows into the day with time. Their relationship can be rhythmic, or it can be one of constantly changing balance, cyclical. For example, for various tasks and activities we carry out in our daily lives, we stimulate our mind (Yin, the spiritual), or our body (Yang, the physical), to suit our needs. But in everything we do, both are present. Depending on what we're doing, whether its studying for an exam or running a marathon, the balance shifts to favour one over the other, Yin in the case of the former, Yang in the latter. Once we no longer need to stimulate our mind or body, we give them time to rest and recover, and both Yin and Yang will once again rebalance themselves.
Coming back to Daoism, it teaches us to be free-flowing, ever-changing, never confined to a single state of being, Wuji Dao (Way of Nothingness). Similarly to how Taiji is existence without distinction, one must themselves always be changing their state of existence, the balance of Yin and Yang must be constantly shifting in order to react to the world around you.
Now, in Naruto, both Yin and Yang materially do exist in the world in the form of energies. Going back to my earlier example of stimulating mind and body, doing these things produces distinct energies. Anything we do with our minds, such as studying, meditating or otherwise thinking, produces spiritual energy, which can be actively manipulated via Yin Release. By similar principle, anything we do with our bodies, such as running, climbing or fighting, produces physical energy, which can be controlled through Yang Release. These energies are inherent to all of existence in Naruto, similarly to how Yin and Yang are conceptually inherent to all things in the real world. Likewise, they are inseparable from each other, and so too are spiritual and physical energy. Both of these energies comprise chakra, as well as the techniques they fuel. Certain techniques and abilities lean further into both Yin and Yang to a greater extent than what you see in techniques from the Basic 5 Elements, but true control over spiritual and physical energies isn't possible until you possess Yin or Yang Release respectively, at least nowhere near the level of power or refinement you see in either. What's most important to note about these 'Releases' is that, despite their names, they aren't entirely separate from each other. No Yin or Yang Release technique is completely devoid of either energy. For example, every Yin Release technique has some level of physical energy in it, and every Yang Release technique has some level of spiritual energy in it, it's merely that one has been favoured over the other via manipulation of the ratio between the energies.
As for Yang's capabilities in the RP, it deals with all things in the realm of what can be called 'life', the ability of objects and beings to act of their own accord. It also interacts with and influences the constitution of other objects by manipulating their physical energy. An example of this would be abilities such as Birth of Nature, which causes Wood Release techniques to grow uncontrollably by forcibly injecting more physical energy into them, and Touch of the Sun and Power of the Sun, which can rejuvenate targets via exposure to large quantities of physical energy, allowing for regeneration of lost appendages and augmenting their physical capabilities in the case of Power. In the case of Ring of Hell, entirely new appendages can be generated. Examples of Yang, or physical energy, being used offensively would include the Eight-Branched Giant Snake and the White Tiger. While both techniques reduce a target's physical capabilities, such as reduced tracking and reaction speeds, and an inability to use physical techniques of higher ranks, they achieve this effect differently. The Eight-Branched Snake does so by producing a venom which actually reduces the physical energy, or vitality, within a target, whereas the White Tiger overloads a target's body with physical energy. This goes back to the concept of ratios between Yin and Yang, the spiritual and the physical, and how Yin and Yang Releases in the RP are as much about manipulating ratios between the aforementioned energies as they are about simply controlling them individually.
That's everything I've gathered from reading and prior knowledge. I might have missed some things or been too general, particularly on the Daoist concepts, so do fill in blanks or correct me on whatever is necessary.