Events don't have categories you can filter them by, but you can add Tags to events, and use those tags for filtering.

For example, if you need to add a tag to multiple events that are related to "Physics", you can assign a tag "physics" to all those events.

To filter all "Physics" events on the front-end, you can use a custom shortcode [ameliaevents tag='physics'] that will show only events with this tag included.