Basically, the topics of ACM are in English, so your English needs to wait, this lz.
It should be no problem.
The most important thing is the algorithm. You can read Ken's book Introduction to Algorithms.
The third is programming ability. In ACM competition, time is also a measure. How to solve the problem in the fastest time and compile and run correctly.
Finally, I think it is also important to consider the comprehensiveness of the problem. Many topics of ACM will have critical situations. How to make your program pass the test of these critical values is very important to examine the comprehensiveness of one's thinking.