Have you ever played with a toy car and tried to make it go around a curve really fast? Sometimes when you turn the car, the back tires might slide out to the side a little bit, and the car might go a little bit sideways. This is called oversteer.
Oversteer happens when the back tires lose some of their grip on the road while turning. This can be caused by going too fast, turning the steering wheel too much, or even by just hitting a bump in the road at the wrong time. When the back tires slide, it can make the car feel like it's going out of control or skidding, but a skilled driver can use this to their advantage to make the car turn even sharper.
Oversteer can be dangerous if it happens unexpectedly or if the driver isn't prepared for it. That's why professional race car drivers practice a lot to get really good at controlling oversteer and making their cars go as fast as possible around curves without crashing.