This summary is not the rule. The rule text controls.
If someone gets hurt and the person or company responsible later fixes the problem or makes things safer, that fix generally can't be used as evidence against them in court. For example, if a store fixes a broken step after someone trips on it, the fact that they fixed the step can't be used to prove they were careless or that the step was dangerous in the first place.
The idea behind this rule is to encourage people and companies to make things safer after an accident. If courts let people use safety fixes as proof of guilt, businesses might avoid making improvements just to protect themselves in a lawsuit. The rule removes that fear so people will fix dangerous conditions instead of leaving them as they are.
There are some exceptions, though. This evidence can still be used for other reasons, like showing that a witness is lying, or proving who owned or controlled the property if that's in question. It can also be used to show that a safety fix was actually possible, if the other side claims it wasn't.
