A CPQ (configure, price, quote) system helps to manage complex sales cycles including things like managing complex variations of products (configure), calculating prices (price), producing quote (quote).  These systems also typically support workflows and approval processes to ensure potential orders don’t get slowed down or lost along the way.  They are often part of or tightly integrated with a CRM tool (such as Salesforce).  For customers running SAP ERP systems, it is also necessary for the CPQ functionality to be tightly integrated to SAP to avoid having to duplicate configuration and pricing logic in two places.