Context #1:

David: So what are you going to do this weekend?
Sam:  I had such a busy and stressful week at work, so this weekend I’m just going to kick back and get some rest.
David:  That sounds good.  Call me if you change your mind and you want to go out and do something.
Sam: All right.

Context #2:

Stephanie:  When I was a kid, I lived way up in the mountains.
James:  Really?  Did you like living there?
Stephanie:  Yeah it was pretty cool.  After dinner, I used to go outside, kick back, and look at all the stars in the sky.  It was so beautiful.  In Los Angeles, we hardly ever see stars at night.
James: Yeah, that’s true.

Meaning:  to kick back means to relax and take it easy. 

This idom comes from the LSI book titled Speaking Savvy.  This book is used to teach Level 5 Speaking classes at LSI schools.  For more information please visit www.languagesystems.com