Do you know the definition of ?
Edit: It's best to post questions about formal languages to the Discrete Math subforum.
I believe this, but no exercise is located in a vacuum. It is supposed to follow a textbook chapter that defines concepts, proves theorems and works out examples. Without going over such material, it is useless to try solving exercises.
The multiplication in this case is the concatenation of languages. That is, if K and L are two languages (sets of words), then KL = {uv | u ∈ K, v ∈ L}. Every word from K is concatenated with every word of L. A special case is K^0. From what I remember, it is defined as the singleton containing the empty word, but this has to be double-checked.
Knowing the definition, it is straightforward to answer the question.