Ktir literally means "very" and mnih means "well."So ktir mnih would mean "very well," although in speech, Arabic mnih comes first then ktir comes after it (i.e., mnih ktir, which is also translated in English as "very well").
yo2borni jamelak habibi bhebak ktir mwah mwah mwah
You are so beautiful : antiii jamelaa jeddan ,, written : أنت جميلة جدا or u can say it in the non-formal Arabic which is easier and more familiar : entee kteer helwee those said for a girl if u want to say that for a male ,, replace antii by antaa and replace Entee by entaa hope this helps :)