In a “Late Binding” workflow, RGB image data is inserted into the layout during separation, and also embedded into the print PDF during PDF export to the print file. The conversion into the print colour space takes place at the last possible moment, e.g. in the RIP of the printing company.
The advantage of this is that all colour spaces are embedded unchanged in the PDF, and the separation can take place as late as possible and thus as specifically as possible. The disadvantage is that the layout designer can never see and control the separated CMYK data and therefore has to give up control of the separation.
Further workflows are Early Binding and Intermediate Binding.