Fortnite Chapter 2 Season 2 has implemented a new mechanic: from now on, you'll be able to throw healing items to your allies in distress. For the mission "Throw different shield or healing items", you'll need to find an healing or shielding item, select it and throw it to one of your allies. The challenge will allow you to complete a task in the Brutus' Briefing challenges to unlock a skin variant for the agent.
For this challenge, it'll be better to land in the Team Rumble mode where allies are more numerous. If you die before completing your quest, you can reappear as many times as you wish.