When you select more than one node, the Node Property panel will let you update properties for all selected nodes. This works when you select multiple nodes through the sketch (hold Control down and click to select multiple nodes) or through the Find panel (hold Control down and click to select individual nodes, or hold Shift down to select a range).
The available properties which may be updated are shown in square brackets [ ].
For example, I may want to update People in my sketch and record the team that they work in, having just created a new Team Custom Property.
I open the Find panel and select the relevant named People:
I now type the name of the team into the Team property:
The Team property is now updated for each occurrence of Hilary in the sketch:
You are able to select nodes of different types; the Property panel will show you which common properties can be updated across the selected nodes. This includes any custom properties you have created: