Question

Give me an example of a unit rate used in a real world sutuation

Answer 1

A unit rate simply means how many of one type of units you get per 1 other type of unit. 
Examples of that:
$300\frac{l}{ s }$

This is rate of fluid flow of some pump for example. It pumps 300 liters every second.

Other example:
$50 \frac{km}{h}$
This is example for speed. Somebody is moving at 50 kilometers per hour (every hour he travels 50 kilometers)