Hi Wilbert, May, might and could are ‘modal verbs’ and indicate degrees of how possible something is or how likely it is to happen. They are very similar but there are slight differences, so it could take a bit of practice to get the hang of the differences. He may go to the shop later. - it is possible - and there is a slight preference towards the action happening. He might go to the shop later. - there is a small likelihood of it happening. He could go to the shop later. - it is possible - but there isn’t much indication of how likely it is to happen. I hope it helps. Let me know if you have any questions. Take care, Triss

Here's a good explanation and some practice exercises: https://www.ecenglish.com/learnenglish/lessons/can-could-may-might-must