Chakra: Chakra is the fuel that powers up the vehicle that is ninja arts(nice analogy ehhhh?). It is the molding of the physical energy, which is present in every cell of the body, and the spiritual energy, which is gained from exercise and experience. Molding the chakra is done by two basic principles: Shape Manipulation and Nature Transformation. Shape manipulation pertains to the ability to give your chakra a desired form while Nature transformation pertains to the ability to give your chakra a desired set of characteristics/ properties. Sometimes, to better mold chakra, ninja use Hand seals. Hand seals are simply hand gestures that allow the ninja to more easily concentrate and mold the chakra into the desired technique.
Ninjutsu: Ninjutsu is the ability to accomplish tasks that would be otherwise impossible to do by a regular person. Ninjutsu is done by two steps: Focusing your chakra and Molding your chakra. Focusing on chakra is your will power to "will" a portion of your chakra to do something. On the other hand, molding is giving your chakra a set of characteristics that will enable you to produce the desired end effect. Think of the chakra flow as our breathing. Normally, it happens passively, without any conscious intervention. However, when you need to you can use your will to control it. Its the same with your chakra flow. Its happens normally without your conscious intervention.However, you can focus your chakra and make it produce something.
Lightning Element: Lightning is a destructive element that doesn't need much focusing of the chakra to be effective. The element can be use to pierce through objects with speed and also use to paralyze your opponent for a few seconds. As shown in the manga, it can be infused with weapons to increase its piercing damage and can be discharged throughout the user body, attacking from all directions.
Strengths and Weaknesses: Lightning is strong against Earth but is weak against Wind. Lightning can be used in conjunction with Water since water conducts electricity. This means that a Water Release technique can be used to increase the damage of a Lightning Release technique and vice versa.
The Uniqueness of Lightning: The only unique attributes that comes to mind is

1) It can be used to paralyze your opponent;and (2), you can discharge it from your whole body, causing it to attack from all directions. You can infuse it within your ninja tools, but that is not unique since you can do that with the Wind element as well.
That is pretty much all I know so far.