yinfa3 as verb in general = benefit u can translate it as it doesn't benefit or it doesn't work in ur sentence ma yinfa3 keda for example if ur daughter do something wrong and u want blame her when u say that's not good or okay it's like ma yinfa3 keda that's wrong well

It doesn't benefit (you for male) هذا لا يعود بالنفع عليكَ It doesn't benefit (you for female) هذا لا يعود بالنفع عليكِ It doesn't benefit (us) هذا لا يعود بالنفع علينا It doesn't benefit (him) هذا لا يعود بالنفع عليه It doesn't benefit (her) هذا لا يعود بالنفع عليها يعود -> return There isn't any equivalent for "it" in Arabic language. My advice for you is to learn classical or modern Arabic before trying to learn any other Arabic dialects.

this is slang for لا يمكن ان يتم الامر بهذه الطريقة It can't be done in this manner

Yinfa3 = يَنفَع from the verb نَفَعَ = to benefit ma yinfa3 keda = it doesn't benefit They say this sentence to someone who said or did something wrong