You say a single word that describes an object or creature. Every target that matches the description within range is marked. You cannot be too broad with your words (I.e. Abberations, Celestials, fiends, etc) but you can search for specific races (I.e. Kobolds, Imps, Humans, Orcs, etc). You also can’t search for specific targets by name. Each marked creature must make a wisdom saving throw or be known. Creatures unaware of the caster make the save with disadvantage, while creatures within 30 ft. Of the caster and are aware of the caster make the save with advantage. Non-sentient objects automatically fail the save. On a Failure, the caster knows the general location of the target. On a Success, the caster doesn’t know where the target is.

At Higher Levels. When cast using a spell slot of 3rd level or higher, the spells range increases by 30 ft for every slot above 2nd.