How to pass a value from the PropertyPane to the webpart in SPFx?

Hi PeterKiers , you need to locate the file where the web part properties are defined. This should be in the YOUR_NAMEWebPart.ts file.

In the interface, you’ll find a default property like description: string.

export interface IYOUR_NAMEWebPartProps {
  description: string,
  lists: string | string[]; // Stores the list ID(s)
}

Then you can access the value by using this.properties.lists