In 10 gallons you have room for 1 small fish that will stay 3 inches or less in size. In regards to needs... yes, the tank would still need to be skimmed, either a skimmer or manually with paper towels on a daily basis and it will still need filtration, circulation, etc.
If you are new to keeping saltwater then a 10 gallon is NOT the way to start. Nano tanks are much harder to keep and stabilize than larger tanks. Minimum for a beginner I would suggest nothing less than 30 gallons, but the larger the better.
I'm not sure who provided you with your current information, but in all truth, a 10 gallon tank isn't suitable for much else than corals/inverts. There are very few fish that can thrive in that size of a tank and most of those are not easy fish to keep. Even a single damsel needs at least 20 - 50 gallons depending on what species it is. Most marine fish get quite large. When it comes to corals in a nano tank then you must be prepared for fragging them properly (each type of coral has its own needs/methods for proper frags) and an outlet for the frags. Even corals will outgrow a 10 gallon tank rather quickly if its a healthy environment.