A CUBE gives items like outfits and weapon skins. By clearing the Daily Quest, you can receive a CUBE Ticket and use it to get a CUBE.
You’ll receive a random selection of items from the roughly 100 different ones available from a CUBE.
You can also choose a specific CUBE item to purchase using the in-game paid currency, SAO Coins.
There are roughly 100 different items available from CUBEs, including outfits, weapon skins, accessories, consumable items, and emotes. The outfits and weapon skins are cosmetic only and do not affect performance.
Daily Quests reset every day and are at a volume and difficulty that should not take up too much time to clear.
There are tons of quests, some of which will have you defeating enemies, collecting materials, and activating Sword Skills and combo attacks. You can get CUBE Tickets and item rewards by completing Daily Quests.
Use the paid in-game currency, SAO Coins, to purchase CUBE items of your choice at the SAO Shop.