Big subject. Many answers depending on context. Here are two images. One shows the very simple use of words like "in" and "on. The other shows "in", "on", and "at" in relation to time. You can see that the answer is very complex.

They’re prepositions that can be used in so many circumstances. If you just started learning English, I can offer you my help! Check my profile!

Hey!! I think the data following in the picture is help you.😊

at I will meet you at school. On I will come on Monday. In I believe in hardworking.