automatons: how should I specifically describe (in words) the language of a regular expression?

For regular expression (alicensed in lettersyes)a I want to learn to describe it in words. I know there is an even number of bs, but how much do I need to explain it? Do I need to explain it enough that each possible chain can be produced from my explanation?
Another example is (a * (baC)) where I would describe it as a string on {a, b, c} where there is the same number of a & # 39; s and c & # 39; s.

Thank you.