Apache OFBiz is an open source product for the automation of enterprise processes. It includes framework components and business applications for ERP, CRM, E-Business/E-Commerce, Supply Chain Management and Manufacturing Resource Planning. OFBiz provides a foundation and starting point for reliable, secure and scalable enterprise solutions.
The OFBiz plugins repository, that notably includes the E-Business/E-Commerce component, is complementary to the ofbiz-framework repository (https://github.com/apache/ofbiz-framework) It includes component that are not necessary for OFBiz to work but add significant features, like the ecommerce one, but not only.
You can find more documentation (asciidoc format), in the docs component. You can also find technical information at https://nightlies.apache.org/ofbiz/stable/readme/html5/README.html#ofbiz-plugin-system