https://www.gamespot.com/articles/fortnite-guide-search-between-a-bench-ice-cream-tr/1100-6459123/

Season 4 of Fortnite: Battle Royale rolls on with a new set of challenges for Battle Pass owners to complete. Week 4's challenges are now live on PS4, Xbox One, PC, and iOS, and this time around, they're made up primarily of straightforward tasks, although a few may still pose a bit of trouble. Here's how to complete all of Week 4's objectives. [Update: Season 5 is coming up on July 12, giving you only a little more time to complete all Season 4 challenges.]

As usual, there are seven new challenges to complete, most of which are fairly self-explanatory. On the easier end of the spectrum, one challenge tasks you with dealing damage with Assault Rifles, which is simply a matter of finding the right weapon and using it to inflict a specific amount of damage to other players.