BAT tokens are meant to be exchanged between publishers, advertisers, and users through a transparent system to reward the attention of online users.
Brave is an internet browser, relying on Chromium (the open-source version of Google Chrome), which integrates with the BAT token. By default, the Brave browser blocks advertisements, prevent trackers and monitors privately the "attention of users" in order to reward publishers accordingly.
BAT are paid to users for visiting websites while publishers get rewarded for their content based on the attention paid to their work. From the perspective of advertisers, they supposedly enjoy benefits such as "better user targeting, an improved ROI, and reduced fraud" for online campaign.