ELI5: How do manual cars work?

I’m currently learning how to drive a manual car and I am having a bit of a hard time. My driving instructor isn’t the most patient person and when I asked him what the clutch is exactly and how it works he said… something, but I was too scared to tell him that I didn’t understand a word. I think if I understood the mechanics of what I’m doing exactly when I press down the clutch and change gears, maybe I could grasp the whole thing a bit easier.