the.com/postcode

means A short code of letters and/or numbers attached to an address so mail and data can be sorted by location.

from Postal codes emerged as mail volumes exploded and manual sorting buckled under the weight — Britain began rolling out its alphanumeric postcode system in the 1950s–70s, building on earlier, simpler postal district numbers from the early 1900s. The word itself is a plain compound of 'post' (mail) and 'code,' born in the age of mechanical sorting machines that needed something a scanner could read faster than a human eye could read handwriting.