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 provides its users with a wide range of options for personalizing their avatar or character. Players can purchase or acquire free items such as clothing, accessories, and other cosmetics.

Roblox is one of the most customizable games ever made. Besides allowing you to make whatever game you can think of, it also allows players to create image IDs to share pictures.