Meaning of the word "be up for" in English

What does "be up for" mean in English? Explore the meaning, pronunciation, and specific usage of this word with Lingoland.

be up for

US /bi ʌp fɔr/
UK /bi ʌp fɔː/

Idiom

to be willing or eager to do something

Example:
Are you up for a game of tennis?
I'm always up for a challenge.