The Glow Stick in Phasmophobia performs the same function as the UV Light. A big difference however, is that the light range is much shorter. On the other hand, when you throw it on the ground it does shine in all directions unlike the UV Light. Using a Glow Stick to find Fingerprints is a bit of a challenge, but it can be done with most surfaces.
When using the Glow Stick you need to keep in mind that it only shines a very short distance. This means you have to get very close to any surface you wish to inspect. Perhaps the best use for the Glow Stick is to use it to mark the room the ghost is in on larger maps.
One of the best examples of this is when 4 people go into a medium or large building with rooms that look pretty much the same and have no distinct differences. Two examples would be the Asylum and High School. When splitting into two pairs to sweep for the ghost, each pair should have one Glow Stick. When you find the room the ghost is in, simply chuck a Glow Stick in the hallway outside the room. This way you and your teamates will find it much easier to spot the room when you return with more equipment.