Complex sentence: Market penetration refers to the successful selling of a product or service in a specific market, and it is measured by the amount of sales volume of an existing good or service compared to the total target market for that product or service.
Split into simpler sentences: Market penetration refers to the successful selling of a product or service in a specific market. It is measured by the amount of sales volume of an existing goods or services compared to the total target market for that product or service.