What is Archaeology in Minecraft?
Archaeology was introduced at Minecraft Live 2020 and was supposed to appear in the Minecraft 1.17 update, but later the developers split "Caves & Cliffs" into two parts and postponed archaeology. Now it will only be released after Minecraft 1.18.

What is Archaeology?
Abandoned archaeologist camps will generate in the world. In these camps, players can find brushes used to clean various blocks and obtain artifacts from them.

Players will also be able to obtain ceramic shards, which can be used to create pots with unique patterns.
It is unknown whether the pots will have any functionality or if they will be purely decorative blocks.

Brush Types
Two types of brushes were shown: copper and oxidized copper.

When will Archaeology be available?
Archaeology will be released after "Caves & Cliffs Part II" (1.18) at the beginning of next year. It is not yet known whether this update will be numbered 1.18.x or 1.19.
We should get details during Minecraft Live 2021 on October 16th of this year.
Video demonstrating archaeology