Could be red eared terrapins or sliders as they call them in America.
Those are the most commonly available.
If it is them then they grow to the size of dinner plates, are very messy, stinky and require at least a 4 foot tank just for one.
I used to keep them when i was younger so they are a lot of work. Filtration needs to be really big to deal with the waste.
I know they look cute now but they grow big fast and will if put with your fish eat them.
They also need a landing spot so they can bask under the lights, not practical in a fish tank.
Best avoided unless you can give them heaps of room.
They also carry bacteria on the shells such as salmonella, so great care needs to be taken when handling and placing hands in the water.
And they give a nasty bite