How to manage INT and EXT scenes and locations, and what does this mean?

Scenes in the list of scenes will appear as:

INT. (interior scene)

EXT. (exterior scene)

INT./EXT. (a scene that happens in both kind of locations: interior and exterior)

When you create a new location, no matter if you create it in the locations tab or inside a scene card, it is set as an interior location.

To change the type of location to exterior or interior/exterior, you have to open the locations tab, enter the scene that you want to change and select the "Type" section, as you can see in the images below: