Will, would, and have are auxiliary verbs used to form different tenses. Will have is used to form Future Perfect, to describe something that not simply takes place in the future, but is completed ("perfected") at some reference point in the future (which is usually specified).

Example; I will have done that by the end of the week.
⇒ I will do that, and at the reference point (end of the week), my action will be over; I will be able to say "I have done it".