What is a medieval queen?

Answer 1

In the middle ages queens were generally the wives of kings. Sometimes they were the rulers themselves, but because they were women they would not be called "king" but rather then feminine version, which is "queen."

Answer 2

That was different in different centuries and countries.

Some queens were queen regnants and held power in their own right.

Most became queens through marriage. They were expected to bear sons, establish ties between her family and her husband's and do charity, but would often engage in a whole range of activities, from embroidery to raising armies.