This summary is not the rule. The rule text controls.
If someone files a lawsuit about a piece of property, that lawsuit by itself does not warn other people about the case. This applies to cases involving who owns the property, or cases involving a mortgage or other claim against it. Just because the case exists in court does not mean buyers, lenders, or other outside parties automatically know about it.
For outside parties to be considered "on notice," the person suing must take an extra step. They have to file or record a formal notice about the lawsuit, following the specific steps laid out in Article 3752. Only after that notice is properly filed will other people be legally considered aware of the case.
This matters a lot for real estate deals. If you are buying property or lending money using property as collateral, you want to know if there is a lawsuit that could affect that property. This rule protects you if no formal notice was ever filed. It also tells people involved in property lawsuits that they need to record a notice if they want to protect their claim against someone who later buys or borrows against that property.