This is a simple sentence because in its entirety it is a single clause. There are no multiple independent clauses connected or any subordinate clauses to make it compound or complex.
Sort of it depends on your point of view of the story
It explains that Romeo and Juliet will face many obstacles because of their families' hatred.
It is an allusion The poem uses Christian imagery regarding the Apocalypse and Second Coming allegorically to describe the atmosphere of post-war Europe.
