How specifically do I need to describe (in words) the language of a regular expression?
The first language can be described as the set of words on the alphabet $\{a,b\}$ with an even number of $b$'s.

The second one is not the language of words on the alphabet $\{a,b,c\}$ with an equal number of $b$'s and $c$'s (this condition would define a non-regular language). You could use greybeard's description or say: the language contains the empty word, the last letter of the nonempty words of the language is a $c$ and if you delete the $a$'s, you are in $(bc)^*$.

It would be safe to provide a formal proof by computing the minimal automaton corresponding to each description.