This is the 6178th most frequent Arabic word.
يكف
"يكف" means "to stop" or "to refrain."
In this sentence, 'يكفيه' means 'is sufficient for him', indicating adequacy.
يكفيه ما لديه من طعام ليومين.
He has enough food for two days.
Here, 'يكف' means 'stops', indicating ceasing an action.
يكف الرجل عن الحديث عندما يطلب منه ذلك.
The man stops talking when he is asked to.
Again, 'سيكف' means 'will stop', showing the action of ceasing due to exhaustion.