How to do good at school?

So as most of you may maybe know, I moved to Denmark this summer and I will be staying here for a year, Yesterday I just started college as a Pre-IB student. I am good at English. Well the problem is that I’ve been living in Iceland for 4 years, there we learn everything in Icelandic except for english class. The last time I learned every single school subject was from 1st-7th grade in Zambia. So I am much used to Icelandic than English, today was the actual first day of studying, we learned Physics and our first lesson was taking a questionnaire which I didn’t understand much of:/ Physics I understood some of it, but not everything….
Now what about math class and history or whatsoever? I will SUCK!

help me please? I need to understand more, I don’t think I am bad at vocabulary, but it’s just that I haven’t been using english 24/7 in the past years.