The future perfect, will + have + past participle, is used to talk about a time in the future by when a particular activity will be completed.

http://www.bbc.co.uk/learningenglish/english/course/intermediate/unit-26/session-2/activity-3

http://www.bbc.co.uk/learningenglish/english/course/upper-intermediate/unit-13/session-1

http://www.bbc.co.uk/learningenglish/english/course/upper-intermediate/unit-13/session-4