Palmitic acid is a saturated fatty acid present in palm oil, butter, cheese, and meat. Your body also makes it, and it forms the bulk of saturated fat in a typical diet. You won't find it sold as a standalone supplement, because most people already get plenty from food. Isolated palmitic acid has no recognized purpose or proven health benefit.
Eating a lot of saturated fat, including palmitic acid, can push up LDL cholesterol and raise cardiovascular risk. Health agencies say to keep saturated fat intake low. Without a standard dose or clear reason for it, taking palmitic acid as a supplement is something to approach with caution.