When it says 'Profile Picture', the little icon of the Avatar is pointed at. As can be see in the Twitter video, it shows that users can go to the Avatar editor right next to 'Customize' and 'Shop ...

Roblox apparently has done this for some desktop users via its icons. As you’ll see in the tweet below, the game has changed the icons for the player and studio programs.

Robux is the in-game currency that is core to Roblox. Users can purchase various items, accessories, avatar upgrades and developer products and can even access games within the platform’s ecosystem.