Click the citizen tab, which is the button of an image of a person. Then click one of the flags appearing next to each of the citizens’ names. It’ll give a basic run down if the stats, then you can click attributes (third tab on the bottom of the character sheet) which gives more info.
The three main stats, mind body and spirit, determine different aspects of your hearthlings. Hearthlings who craft (carpenters, masons, and blacksmiths) will work best with a high (5 or 6) Mind for the crafting, and a mid (4 or ) Body for making fine materials. Hearthlings who work (farmers, trappers, and workers) do well with a high Body and low (1 or 2) Spirit so they work well and will run from danger. Hearthlings who fight (footmen) do well with high Body and high Spirit so they can fight well and aren’t probe to run unless ordered to.
Not a huge deal. Every Hearthling can do every profession, and it works. The only possible exception is footmen: footmen need a high courage (spirit) stat, or they will can be afraid of the monsters they are supposed to be fighting. Obviously, some things make more sense than others (trappers should be able to move fast, high-mind carpenters level up faster, footmen do better when they have more HP (higher body)), but the game will work fairly well, especially in peaceful mode, if you simply assign randomly.