This video discusses the concept of mapping entries in a data integration project. Mapping entries define the relationship between attributes in the source and target environments, specifying where to place the value from a source attribute and how to modify it if necessary. The example given is of an acquisition where the source and target companies have different attribute names for employee identification. The video explains how to modify the mapping entry to ensure the correct values are written to the target attribute. It also mentions more advanced options and the ability to remove mappings.