Sir Gawain and the Green Knight is about Sir Gawain, a knight of the Knights of the Round Table, who accepts a game from a mystery man called the Green Knight. The challenge means that if any knight strikes the Green Knight with his ax, then they will receive a blow from him in return in a year and a day.
When the Green Knight challenges the knights to a game, king Arthur accepts it, because no one would, so he could defend the honor of the kingdom and the Knights of the Round Table. Then sir Gawain volunteers for it right after king Arthur, saying that losing king Arthur would be a huge loss compared to losing him.
Despite his praise of the fellow Knights, Gawain is also subtly degrading them, claiming,
“When such a boon is begged before all these knights,
Though you be tempted thereto, to take it on yourself
While so bold men about upon benches sit.
That no host under heaven is hardier of will.”
Sir Gawain is comparing the other knight sitting “upon benches”, as opposed to his desire, “To be gone from this bench and stand by you there”. Despite his familial connections to the King, Gawain must plead and convince the King to take the challenge, whereas his fellow knights have not put themselves forward, unaware of the great threat that the King would be facing. The concluding statement of the excerpt,
“The court assays the claim.
And in counsel all unite
To give Gawain the game
And release the king outright.”
demonstrates that despite his lower social standing within The Court, Gawain was deemed honorable enough to take the challenge on behalf of the King.
Finally, the entire story is an adventure where sir Gawain goes on a quest to find the green knight and complete his challenge.