What's the time signature (in music) of the song "Last christmas" by cascada? If you're not going to answer this properly or don't know the answer, please don't answer. Let someone else answer. (also, DON'T do this for free points; your answer will be reported) If you don't know what a time signature is, here's a definition: A time signature tells you how the music is to be counted. The time signature is written at the beginning of the staff after the clef and key signature. Time signatures consist of two numbers written like a fraction. The top number of the time signature tells you how many beats to count. This could be any number.