If business is now a global affair, then the export-import business is important, lucrative and necessary. An export-import agent is not a broker --- the agents are lower on the business totem pole.
Most properties are measured using a number and a unit of measurement. The unit of measurement is a standard amount. The number compares the property to that standard amount. This means a tree that is ten times as tall as a meter stick is 10 meters tall.
Measurement is a process that uses numbers to describe things based on what we can observe about them. This is done to be able to compare them to each other. We can measure how big things are, how warm they are, how heavy they are, and lots of other features as well. Units of Measurement provide standards for our comparisons, so that the numbers from our measurements refer to the same thing. For example, the metre is a standard unit to measure length.