What does it mean to understand maths?

I've been memorising methods for most of maths atm, but I don't think that's the correct way to learn maths. I've been told that maths is more focused on understanding rather than memorisation. What does it mean to truly understand topics in maths, and how can I achieve that?

i like to think of maths as learning another language, you need to know how to apply the rules and there’s no just memorising it and expecting it to stick, you need to truly understand it like you’d do with a language and then you likely won’t forget it. that’s how it see it that is, and it seems to work for me as i personally don’t forget maths concepts very often so that might be how it works

okay thanks, at what point can I say that I understand something? when I get the questions right in a topic? I also seem to always forget maths concepts even after a week