That would be a common goldfish. Looks like it's probably a young one that may still be getting its colors. (Young ones start out all black and gradually get their colors as they mature.)
A few tips...
If this is your first time having a fish, please be aware that you need to buy liquid drops from the pet store to remove the chlorine from the water. Do not use straight untreated tap water; also treat it before adding to tank.
Be sure to get a good filter and air stone if you don't have one.
Try to give the tank a cleaning and new water once a week. A 25% water change is usually good. Half or up to 75% water change once a month is also recommended.
Never change 100% of the water, as too much of an abrupt change in water conditions can put a fish into shock and they may possibly die. (Goldfish are hardy, so sometimes they pull through...but sometimes they don't.)
Also, when adding new water, make sure it feels close in temperature to the old water still in the tank. Likewise an abrupt temperature change can also cause shock. No need to be exact though, as long as it feels similar when you put your hand in it, it should be fine.
Once it has warmed up to you and gladly taking food, see about giving it a pea once a week; skin removed. (Aim for soft ones, avoid any that are too hard.) Many fish love them, esp goldfish, and it will help prevent fishy constipation that the store bought foods can commonly cause.