What does the date on cottage cheese refer to?

Sealed commercial containers of cottage cheese usually carry a "sell by" label, indicating how long a retailer can stock it; “best if used by,” signifying when the product’s quality starts to deteriorate; or a "use by" date, indicating how long the product will stay fresh at home. This date applies to the refrigerated, unopened container of cottage cheese, and relates to its quality NOT its safety.
 
Source(s):
USDA Factsheet: “Food Product Dating”