what's an epic poem, for me?

According to the Cambridge dictionary, epic "describes events that happen over a long period and involve a lot of action and difficulty".

When I read Beowolf, it was really hard to understand it, because of its english. So I looked up on the Internet what is the poem about. Now I can come with a definition.

Taking into account the definition and what I think, an epic poem is a long story told by someone with a hero, structured like a poem, perhaps with rimes, etc.