Situational Dialogue 1
A: Are you free on Sunday?
B: Yes, I guess. What’s the plan?
(free here means available.)
Situational Dialogue 2
A: May I use your phone?
B: Feel free.
(If you permit sb. to do sth.,you can say “feel free”,which means go ahead. )
Situational Dialogue 3
A: I got this ticket for free.
B:You are kidding me?
(You can’t get anything for free in this world.=There’s no such thing as a free lunch.)
Complement:
Be in free fall
Share prices are in free fall in Tokyo this morning.