quantity, unit and SI system?

Question

help me defind them?

Answer 1

The SI is the Standard International way to measure something.

Let's take length as an example.

The standard SI unit to measure length is a meter. So the unit is meter. The quantity relates to how many meters in the item you are measuring.

The same will be true for other SI units, such as time (seconds), mass (grams), volume (liters)