Answer:
It depends. Some systems... for example, the Hebrew... sometimes have 12 months and sometimes have 13 months in an effort to keep the calendar more or less aligned with the seasons. In other systems, like that used by Islam, they basically say the heck with the seasons and use the same number of months in every year, so their calendar "drifts".
In any system, the answer is almost certainly going to be either 12, or 13, or sometimes 12 and sometimes 13, because there are between 12 and 13 lunar months in a solar year.