This page of the Assassin's Creed Valhalla game guide includes a detailed walkthrough description of A Desperate Bounty side quest.
Award for completion: 1200 XP.
In the place indicated in the image above you will meet Hrorek, who will immediately start calling for help. From the conversation, you will find out that some Jarl was kidnapped by bandits and if you do not help him, he will be killed.
Jump on a horse and follow Hrork. The situation seems quite suspicious, so you better keep your eyes peeled.
When you get there, it turns out that Eivor himself was caught in an ambush. Awelcoming committee of several thugs awaits you on the spot. The opponents are armed with two-handed clubs and are able to deal significant damage but they are very slow.
Their leader, Olaf, will sometimes use a clever trick with a cloud of dense smoke that will limit your visibility. As soon as he tries this trick, step back, and wait for the opponents to get close to you.
After the fight is over, talk to Hrorek. he will tell you that Olaf forced him to lure victims to the bandits who would rob them. Fortunately, the bandits will no longer threaten anyone else.