Most of today's RPGs have a crafting element that includes a way for characters to make their own weapons, food, or potions. In Baldur's Gate 3, there's only one such profession available, Alchemy, and it be used to concoct a variety of useful materials beyond just the usual potions and elixirs.
Baldur's Gate 3: Complete Alchemy Guide
Here's everything you need to know about Alchemy in Baldur's Gate 3.