Every position on the earth's surface is localized through the measurements of latitude and longitude, also called geographical coordinates.
The longitude can be East or West, is expressed in degrees and can reach a maximum value of 180° on the antimeridian (ie the meridian opposite to that of Greenwich) and measures 0° on the meridian of Greenwich.
Normally, longitude is expressed in degrees/minutes/seconds, and nautical GPS often display tenths of a second.
Italy is between 18°31'18" and 6°37'32" east longitude.