Google wowed everyone when it unveiled Night Sight photos alongside the Pixel 3. Many OEMs have since tried to replicate Google's witchcraft, but none have been able to match it. Samsung is the latest to try with an OTA on the Galaxy S10. You probably don't have the update yet, but it's coming.
Samsung's "Night" photo mode is in the mode selector strip next to panorama. When selected, the camera app reminds you to hold your phone steady while taking night shots. That's presumably because it uses a similar technique as Google, taking multiple frames and stacking them. That should allow you to brighten photos in very dark areas, but the quality will depend on the strength of Samsung's algorithms.
So far, this update has only appeared in Switzerland. It includes the latest April 2019 security patches as well. We don't know when it'll hit US devices—that's up to the carriers.