Cats like to hunt. Unfortunately, many cats also like to eat what they catch and kill, which includes rodents, birds, lizards, squirrels, and anything else they can catch and kill.
Besides killing wildlife, a more serious problem is that cats can pick up diseases from wildlife. So it’s generally not a good idea to let your cat eat wild animals if you can help it. It’s safer to give them commercial cat food instead, but that’s only exciting to eat if you cat can hunt down the person delivering that food to your home.