You map helps you keep track of where you are in game, where important locations are, quest objective areas, and more.
By default, the map shows the area you are currently in. You can see this at the top of the map, in the second drop down menu. If you wish to see a different region, simply select the one you want from the drop down menu. You will be able to see towns, dungeons, NPC types, and quest objectives for the region you are viewing.
The third drop down menu, at the top of the map window, will allow you to view points of interest for the region you are looking at. These views will be close up, detailed layouts of the area, which will more clearly show any NPC's or quest objectives located there.
If you feel like your map is too cluttered, or you are looking for something specific, like a type of NPC, you can use the filters on the right side of the map to narrow down the icons displayed. Options include, but are not limited to showing/hiding part and guild members, quest objectives, and specific types of NPC's.