A percent off of a product means that the price of the product is reduced by that percent.
A percent off of a product or service is a common discount format. A percent off of a product means that the price of the product is reduced by that percent.
Formula to calculate percent off.

Example:
A supermarket put an offer of 5% off on a product that costs $200. Determine the percent off.

Thus, the percent off is $ 10.