The short form of "you have". Here is the part that trips learners up: it is normally only used when "have" is a helping verb, forming the present perfect — "You've finished", "You've been waiting long". When "have" is the main verb meaning "own" or "possess", people usually do NOT contract it: you say "You have a lovely house", not "You've a lovely house". (Some older or British speakers do say the second one, so it is not impossible — just not what you should copy.) Like the other contractions, it belongs to speech and to friendly writing; formal writing prefers "you have". In fast speech the 've often shrinks to almost nothing, so "You've got it" can sound like "Yuv got it" or even "You got it" — which is also a real casual American way of saying it, with the have simply dropped.