A "location name" is the human-readable name of an area in a game map. Depending on your HUD, you can even see the name of your current location all the time. But normally, the location name is only shown when you use team chat. You can just chat something like "<-----" or even "." to inform your team mates where you are.
Sadly, none of the original Tremulous 1.1.0 maps feature location names, and it is rarely seen that mappers build location names into their maps, even though they are a great and relatively easy to implement feature.
Mapper-tip: To implement a location name, click the right mouse button in NetRadiant in the 2D view and select "target_location". Also, open the "entity inspector" (key "n"). The rest is explained on screen. To have the proper name in effect in the right location, you kinda have to paint the map using target_location entities every once in a while.