used with units of measurement to mean one such unit.
what does "with"means?

Question

Answer

In the phrase "used with units of measurement to mean one such unit," the word "with" means "in connection to" or "in association with."

So, the sentence means that something is used in association with or alongside units of measurement to represent one unit of that measurement.

For example:
* "A kilogram" is used with the unit of measurement "kilogram" to mean one kilogram.
* "A mile" is used with the unit of measurement "mile" to mean one mile.

Does this help?

Answer

WITH has the same meaning in both examples below.  WITH=together

1.  I walked WITH you.
 2.  x  used    WITH units of measurement.