What are unit sales?

Unit sales is simply the number of units that a business sold in a given period for time. Assume a business sells widget A for $10 each and widget B for $5 each. Monthly sales volume may be $1,000. However, unit sales information will let the company know which widgets are selling. Did the company sell 100 A widgets and no B widgets? Did the company sell 50 A widgets and 100 B widgets? The unit sells will answer that question.