Answer:
It shows that Grendel is not happy about the ever happiness and the loud enjoyment he hears everyday coming from King Hrothgar's mead hall. He is envious of the joy he hears from the hall.
Explanation:
The old English epic poem "Beowulf" was a famous story of how the title character Beowulf saved the Dane people from a terrorizing monster Grendel and his mother. He became king of the Geats and later on, slayed a dragon too.
The lines from the extract provided are from Chapter II: Scyld's Successors, where the poem shows the party and enjoyment at the mead hall. The men were having a great time in the newly built hall, feasting and playing music. But not far away from them, lives the monster Grendel who envies them. He lives alone and has no one to enjoy with. At this time, he hadn't killed anyone.
The lines shows that he had been hearing the joy, laughter and music from the hall daily, which he "endured for a seasn, bore it bitterly (and) bided in darkness".
