This allows you to change the Quantity UOM of a formulation input when in a % calculation path. When you change the UOM the input's quantity will be converted to the UOM you have selected. This feature is explained further in the 6.1.1 Formulation Enhancements training video (slide 8 & 9) available on the collaboration sites.
Hope this helps, let me know if you have any questions.
Can you post a link to the collaboration site please?