The future perfect tense is the future of the present perfect tense. Compare the following examples:
Present perfect tense:
I have finished reading the book.
Future perfect tense:
By the end of this week, I will have finished reading the book.
Present perfect tense:
He has completed his assignment.
Future perfect tense:
By next month, he will have completed his assignment.
Present perfect tense:
They have graduated from the college.
Future perfect tense:
By the end of this year, they will have graduated from the college.