Beat and tempo
What's a "beat?"
People commonly use the word "beat" to mean "a pattern (or rhythm) played by drums." The thing you're making when you create and play patterns in these lessons is "a beat."
But, confusingly, there's another use of the word "beat," which means "a regular, repeating pulse that underlies a musical pattern." People tap their foot along with "the beat" in this context.
The speed at which your patterns play back is called the tempo. Tempo is measured in beats per minute or BPM. So if we talk about a piece of music being "at 120 BPM," we mean that there are 120 beats (pulses) every minute.
Some types of musical patterns have a very clear underlying beat, while others have a more subtle or implied one. To hear a steady beat, add notes on the Kick line at the positions labeled 1, 5, 9, and 13.