This view will color all buildings in the city that import or export commodities outside city borders.

If you have a developed industry, then he probably creates surplus of goods and exports them outside the city. But it you have small industry or have a directed industry and no general industry, then shops will import commodities from outside.

A good idea is to have slightly more of directed industry (resource one) than general industry, but you shouldn't overdo it, as too intensive exploitation might quickly use all precious resources, and a situation where there is no import to your city is in practice impossible.