To see what the artifact can do, first drop it and pick it up. Check your message log to see if it mentions something. Usually you can get an idea of what the artifact does to you. Also try wielding it, which could also give different effects.
Some artifacts have charges, and if they do they usually come with charges already - so if there’s not there isn’t any. If there are, activating them will have some other effects that could happen, and it’ll recharge on its own in different ways, most commonly doing damage to your survivor or inflicting pain.
Warning: artifacts that do have charges can have problematic effects when activated. Probably the most problematic is activating an artifact and it releases a wall of fire surrounding you. If you activate an artifact and it asks you which tile you want to activate the artifact in, do it far, far, far away from your survivor.