When you pluck a guitar string, it vibrates to and fro. You can tell how fast the string is vibrating by listening to the pitch it produces. Shorter strings vibrate faster, and make higher pitches. Longer strings vibrate slower, and make lower pitches. The scientific term for the rate at which the string vibrates is its frequency. You measure frequency in hertz (Hz), otherwise known as vibrations per second. The standard tuning pitch, A440, is the pitch you get when your guitar string vibrates to and fro 440 times per second.
The main takeaway here is that you don’t have to follow a typical form if you don’t want to! There’s so much great through-composed music, and sometimes, it can be really freeing to embrace this kind of writing.