Minecraft wiki entry for Trading, associated text: Villagers without a job overlay are unemployed and cannot trade. They wear biome outfits without a professional overlay. An unemployed villager gains a profession by claiming an unclaimed job site block. For example, an unclaimed cartography table converts an unemployed villager into a cartographer when the villager claims it, and both the villager and the table emit green particles. An inaccessible (or destroyed) job site block causes the connected villager to lose its profession, but that does not affect the player's popularity in the village. If the player attempts to trade with an unemployed villager in Java Edition, the villager grunts and shakes its head.