https://www.gamespot.com/articles/ps4-501-update-released-doesnt-do-much/1100-6454345/

Earlier this month, Sony released the major new PlayStation 4 5.0 update that added new features and functionality. Now, the next patch has arrived, but it does not do nearly as much. PS4 5.01 is out now, and the patch notes are one line long: "This system software update improves system performance."

If your PS4 is in Rest Mode, this small update should be applied automatically. If not, you'll be prompted to install it the next time you boot up.