From Maps for MediaWiki

Geocoding is the process of turning an address into coordinates. Geocoding is supported all throughout Maps, meaning that wherever you can specify a location, you can do so either with coordinates or with a human readable address, which is then geocoded.

Since geocoding happens in the background, you generally do not need to pay attention to it. For instance, when displaying a map with markers at certain addresses, Maps is automatically geocoding for you:

{{#display_map:New York City; Berlin; Brussels}}

Geocode parser function

Sometimes you might want to turn an address into coordinates that you can then use for something like display. This can be done with the #geocode parser function.

{{#geocode:New York City}}

Result: 40° 42' 45.82" N, 74° 0' 21.65" W

For more details, see the #geocode parser function documentation.

Wiki configuration

Maps geocodes by making web requests to a geocoding service. This service can be configured per wiki via egMapsDefaultGeoService. The default service is "nominatim". See the maps settings file for more geocoding related settings, such as how long results should be cached.