A quasi-adjective meaning something is a good deal, economical, or offers good value for the price.
今週の特売はまとめ買いするととてもお得です。
This week's sale is very economical if you buy in bulk.
ポイント還元でさらにお得になりますよ。
You'll get even more value with the points rebate.
大容量パックは一回買うとお得だが、保管場所を考えてからにしよう。
Bulk packs are economical to buy at once, but consider storage space first.