Welcome to the Make community!
Below the field, it says:
The maximum number of events that can be scheduled using this scheduling link
Could you tell us which words you do not understand?
The “Maximum Event Count” is like a limit on the number of events everyone can schedule/create using this particular scheduling link. If the maximum event count is, let’s say, 10, it means others can use that link to create up to 10 events. Once this limit is reached by everyone combined, others can no longer use this link.
If you are not sure what to insert into this field, and/or you want it to be used unlimited times, simply put a large number like 999999