An is the indefinite article in this sentence. A indefinite article is usually a or an (pronunciation word)
The story starts when the Oracle of Delphi warns Acrisius, King of Argos, that his own grandson would kill him. Fearing that this prophecy would come true, he locks his only daughter, Danae, into an underground bronze chamber, to keep her away from all men.
The humans arms felt like a snug nest.
nest meaning comforting like a home, a really nice blanket and such. the others don’t really make sense about feeling safe if you put it into literal context
But what’s the information?