Thank you what do they eat? They have been feeding her food for red sliders. I have Sulcata Tortoises so this is my first turtle and want to make sure I give her the best care.
African helmeted turtles are omnivorous, although they probably lean towards the carnivorous side. Make sure you include commercial turtle pellets in her diet. Depending on what they were feeding her before, you may be able to continue with the same food.
I did some further reading on African helmeted turtles. They're predominantly carnivorous. They're supposed to be fairly hardy and make good starter turtles. Don't plan on getting her any tankmates.
For a North American "equivalent," think mud turtles, although African helmeted turtles are probably better swimmers.