English Grammar A1 Level: A modal verb is a type of auxiliary (helping) verb  that has no meaning on its own but it modifies the main verb, changes  its meaning and gives more details about the action.

The verb can is a modal verb  used to express the idea of ability or opportunity, to express the  possibility or impossibility of an event or action happening and to ask  for or give permission.

https://open.books4languages.com/english-a1-grammar/chapter/can-modals-of-ability