Ever since the 1.14 Village and Pillage Update, villagers have become a very important thing in our Minecraft worlds. In total there are 13 types of villagers (excluding normal villagers, nitwits and wandering traders). Each villager profession requires a special workstation block, and by breaking and replacing this block, you can change a villager's profession. When you get a trade you like, trade anything with the villager and the villager will keep the trade and become locked into the profession (meaning that you can't change it again). Anyways, enjoy making all of these workstation blocks.

Credits: I got the block textures from the Pixel Papercraft Block Generator: https://generators.pixelpapercraft.com/generator/minecraft-block

More info on villager professions: Beebom: https://beebom.com/minecraft-villager-jobs-explained/