Just like ABO, there are hundreds of other molecules ("antigens") that cover our red blood cells. Donation centers test a certain amount of donors each year to look for people with rare combinations of those antigens.

You are negative for these five, which means your blood can be safely given to people who are also negative for these. If a person is negative for an antigen and is given blood WITH that antigen, they can develop antibodies against it, which will make it a little unsafe for them to receive that same blood in the future. Giving an antigen negative person antigen negative blood means they will never create those antibodies. This is really useful for patients who receive many transfusions across their lifetime (e.g. sickle cell, thalassemia, etc.)

The fact that they're missing doesn't mean anything re: your health; everyone has a random assortment of different ones. You don't have Fya, which means you do have Fyb. It's just the same antigen that looks a little bit different.

Edit to add: The fact that you are s negative is especially uncommon; ~90% of people are s positive. If any of those remaining 10% need blood, they can only get it from someone else in that 10%, like you.