Sakura will explain it to her, probably in a way where you have to choose to be either a ninja or follow your heart.
"I remember my young ninja days," Sakura said remember such a cruel time. "I trained to become a medic, to save my comrades, Naruto was strengthing his inner demons, while your dad...was battling his own." Sakura sighed looking down. Sarada looked up. "Mama?...you mean the Uchiha massacre don't you..." Sakura looked surprised. " I guess I couldn't protect you from the truth for too long, you've inherited my thirst for knowledge." She said playfully flicking Sarada's nose. "Was Pa..."Sarada stopped. "Was he...bad?" Sarada said looking sadly. Sakura hated to see her daughter look this way. " He was troubled," Sakura said wrapping her arms around Sarada. "From a young age, your dad has been manipulated, for different reasons, out of love to protect him, for his power, and this cosmic curse that use to follow the Uchiha bloodline but you don't have to worry about that," Sakura said as she found her self-beginning to ramble. "Your papa, he was lost. At one point the entire nation was after him. Even the leaf, wanted to....anyway that Naruto has always been a friend even then he couldn't bring himself to even think of harming Sasuke-Kun." Sakura stopped and turned away. "What about you momma?" Sarada asked in a low voice. "There comes a time in a ninja's like where she will be forced to choose. The way of the Shinobi or to follow your heart. Ninja should be void of all emotion, I...struggled with that. I tried to...maybe if I did it he would be at peace, no one could hurt him...I cried and thought it over. I met him at that spot....it looked like him, but he was different...those eyes. But even then I couldn't...."Sakura stopped as she began to tear up. She turned to Sarada.
"Sarada. Promise me on the thing, if you are ever feeling anything, just let me know. Know that you are always loved, and even if something happened to me or your Papa, know that we will always love you, and I will always be with you." Sakura said tapping her forehead.
"I know Mama." Sarada said laying her head on her mothers chest. In a cold voice Sarada muttered."Mama, what is it like to kill someone." Sakura was caught by surprised. She wanted to tell her that she would feel nothing and that your quickly get over it. Sakura rubbed Sarada hair. "Oh my sweet angel, I'm a medic, I protect life. I try not to think about taking them." Sakura said. "But you know that guy, who Dad and the Hokage is fighting...what if....they aren't enough...and they get us..." Sarada began. "Hush, your father is the strongest guy I know, and he will stop at nothing to protect us from threats, that's why he's always out there. And Naruto, he is one tough guy to take down...but, that alien guy wouldn't dare come back if he know's what's good for him, because with these very hands, I will rip his heart out from his chest."