What did Boaz mean by "do the part of a kinsmen"?

Ruth 3:13

NKJV - ¹³ "Stay this night, and in the morning it shall be that if he will perform the duty of a close relative for you - good; let him do it. But if he does not want to perform the duty for you, then I will perform the duty for you, as the LORD lives! Lie down until morning."

Clarify • Share • Report • Asked June 19 2015 • virginia watts