The search is based on the coordinates stored in the Wikipedia articles. They are compared to the current location of the device that displays the page (of course, it is much more accurate for mobiles with GPS). Your location is shown on the map by a flag symbol. Searching is within a radius of 10 km (Wikipedia does not allow bigger range). You can choose your language - abroad it may be useful - to switch the language, because by default English Wikipedia is searched.
The results are displayed on a map from which you can open a link to the Wikipedia article itself. The map can be moved - you can click or tap on the new location - the location is updated and new search could be made. You are free to browse Wikipedia everywhere on this planet :-)
Enjoy and let me know!