Notice the two small red triangles pointing down from the two lower icons. These locations are below where you're currently standing.
In the Alchemy Lab in the Wine Cellar below Corvo Bianco are two tables.
The Eastern one (center of the room), about which you ask, allows you to turn species specific mutagens into generic mutagens. You can finally turn all of those pointless werewolf mutagens into far more useful (lesser) red mutagens! This is most valuable for purchasing Mutation upgrades in your Character screen.
The Western table (in the alcove) allows you to recharge your potions & grenades w/o spending time meditating. Given that the bed upstairs also gives you such nice buffs for spending only one hour, I don't make much use of it.