Usually the speed or tempo of a beat is measured in BPM , or B eats P er M inute. A BPM of 60 would have one beat every second. Every tune or musical score has a specific rhythm to it. Here's an example of a song with the just the musical notes , and here's the same song with rhythmic tapping only . I'd bet anything that the song you're listening to has a syncopated rhythm.
Syncopation is when there's a note or tap on the off beat.
Here's the dictionaries definition of sycopation. You can hear the difference in these examples. Here's the same tune with a syncopated rhythm . It's a hard thing to explain what notes and tones are in words because they are something you can only hear. Basically, music is made up of a series of tones played in a specified rhythm.