APY is the abbreviation for Annual Percentage Yield. In simpler terms, APY can be described as a method to measure how the interest compounds over a specific period of time. Compounding interest is the interest you earn over a period of time on your initial amount as well as the interest you have earned.
If APY for a certain coin is 90% so you will earn 90% profit on your investment after a year. If I invest 100 Cake on Pancakeswap with an APY of 90% I will have 190 Cake after 1 year.
To see how much you will make in 1month, you divide APY / 12. So in our example 90/12 will make 7.5% , means you we will get 107.5 Cake after 1 month . But if you have compounding turned on your next month will be calculated on last month profit as it keeps accumulating .