I think idiomatic expresions are phrases whichmean something and is not the same when it is translated how it is, i don't know how to explain it
an example of this can be
pulling someone's leg: it means make a joke
what's up with:what's wrong with
you're kidding!: are you serious?
what are you up to?: what are you doing?
tell me about it:I completely agree with you
Who cares:it doesn't matter
actually I'm not very sure if I'm right, but i think is that
I'm a studdent too, so I can be wrong
Student or Learner