Help!!!

Hi, so I really need help in math. I think I'm just memorizing problems and equations more than understanding it. Because when I think i understood the concept of the equation or things that teacher has explained, I can't apply it to problems. And even if I can apply it to problems it takes so long to solve it. Which is bad during time limited tests. And I noticed that if I seen the equation somewhere I can solve it because I memorized it, not because I understand it. So can anyone give advice on this, and on how to solve problems quicker? And pls give tips on other things i should know to get better at math. (Sorry if it's hard to understand, English isn't my first language)