There are a lot of names for it (especially depending on what type of animal does it): pet urine stains, brown spots, bunny spots, they are all basically the same thing. When an animal urinates on your lawn, the excess nitrogen in the urine gets spread out over your grass causing parts of it to become brown and sick. If left untended, a large part of your lawn can even die over time.
Dealing with bunny spots in the yard is essential, as you definitely don’t want the cute creatures ruining your lawn. While it’s fine if they tackle the grass around your lawn, the lawn itself might be a part of your yard that is painstakingly tended to, so you don’t want some furry creature with cute, long ears messing it up!
The best way to deal with the problem is by planting herbs like lavender around your lawn. Rabbits tend to avoid herbs that have a strong odor, so the herbs will act as a somewhat invisible wall around your lawn that the rabbits will want to avoid.
If the bunnies have already peed on your lawn, you should immediately water it and clean it and apply a good organic fertilizer, thereby neutralizing the excess nitrogen before it gets a chance to affect your yard.