release date; day something goes on sale
Used for the date a product, book, CD, game, etc. becomes available for purchase.
The release date for the new game is the 10th of next month.
I'm looking forward to the release date.
発行日 is used for the date of issue of publications, tickets, or official documents, whereas 発売日 focuses on the date of sale to the public.
Compound of 発売 (release, sale) and 日 (day).