preposition
a word that shows the relationship between a noun or pronoun and other words in a sentence, in this case indicating the action of listening to something
It is imperative that you hearken to the advice of your elders.
Hey, you should hearken to what your boss is saying.
Dude, you gotta hearken to the new album, it's fire.
In order to succeed, one must hearken to the whispers of opportunity.