advance reservation; pre-order
Used for booking or ordering something before its general release or availability, such as tickets, products, or services.
I pre-ordered the new game.
Advance reservations for the concert start next week.
予約 is a general reservation or booking, while 先行予約 specifically means reserving ahead of the official release or general sale.
Compound of 先行 (preceding, going ahead) and 予約 (reservation).