Levels: All levels
Idiomatic expressions - Idioms - give English its color and vitality. They are indispensable to the daily speech of the people and to the language of newspapers and books, television and movies.
Whenever you hear a phrase whose meaning cannot be understood even if you know the definitions of the separate words involved, you have probably encountered an idiom.
Listen to the first episode - "Having a Ball" - and work on the meanings of the idioms spoken during the dialogue.
Have fun!