I've not studied in class 11 due to covid. And I am very much weak in Accountancy and Maths, but I want to do BBA. What should I do?

It's alright! It's not a big issue that can't be overcome. You still have time. Instead of focusing on that what you lose, now start focusing on what you have. Even if you give 1-2 hours daily to it, you can easily cover it up. But it requires consistency and hard work. So, be relaxed and make a pro