The Opportunities module allows you to track leads, before sales. It adds an additional layer between your customer and your quotation/order. One customer record can have multiple opportunities against it and you can track this independently from the customer record. For example, a returning customer to your business is a second opportunity when quoting for a different room.
Note that when Opportunities is enabled in EQ Professional, the sales pipeline, previously shown on Customer > General is moved to each opportunity instead. The pipeline within Dashboard is not used, and there is a new section in Dashboard for Opportunities reporting.
Opportunities can be linked to at least 1 quotation and each contact history entry can be attached to an opportunity. This helps when searching by opportunities (see the projects help further down).