Q. What do you like the most about your best friend?

☞ She apologize her fault quickly and play with me easily. -> She apologizes quickly if she made a mistake and we play again like nothing happened. 

=> Corrected : The sentence is corrected grammatically. 

Q. Make these sentences into English

-뭐가 필요해?

☞ What do you need? ​

-네가 무슨 말을 하는지 모르겠어.

☞ I don't know what you are talking about. -> I don't know what you mean.

=> Your sentence has a correct grammatical structure, but this has the correct usage/ expression. 

-작동이 안 돼.

☞It doesn't work.  ​​