Hi there, you can either use Flares (https://bdocodex.com/us/item/215/) which you can craft or buy from marketplace or fireworks (eg. https://bdocodex.com/us/item/65215/) which are event based rewards to reveal people using Camo suits to hide their name.

There's also a skill in the game that allows you to reveal it. Shai has one of those skills called "Come out, come out". I don't think there are other skills from other classes that do this but I could be wrong.