There are two types of expiration dates on food products: the "use-by date" for safe eating and the "best-before" date for eating for optimum taste. Both of these expiration dates are given for unopened products that have been stored according to the labeled storage method.
Use-by dates are indicated on lunch boxes, sandwiches, and other perishable foods, so be sure to follow the expiration dates. The best-before date means that the food may not retain its flavor at the expiration date, but it does not mean that it is inedible. However, in the case of both labels, once the package is opened, it should be consumed as soon as possible regardless of the expiration date.
In Japan, the date is displayed in the order of year/month/day. (2022.4.1 means April 1, 2022.)