Time signatures tell you how many and what kind of notes per measure there are.
The number on top is the number of beats per measure, and the bottom number is what kind of note get the beat.
Bottom Number Value
2 =Half note
4 =Quarter note
8 =Eighth note
Top Number Value
3/4 is 3 quarter notes per measure
5/2 is 5 half notes per measure
6/8 is 6 eighth notes per measure
Common Time - Same as 4/4
Example: a half note = 2, a quarter note = 1, a whole note = 4.
Cut Time - Same as 2/2 time
Example: a half note = 1, a quarter note = 1/2, a whole note = 2.