What it means to brown meat is to partially cook the meat before you add it to other dishes.
The browning of the meat is a process of partially cooking the surface of meat to help remove excessive fat and to give the meat a brown color crust and flavor.
You can brown the meat in a skillet and then transfer the meat to other dishes to cook it fully.
Such as if you want to brown some meat and then put the browned meat into a slow cooker or pot of soup etc.
You can however just place raw meat directly into a slow cooker or a pot of soup or other dish and cook it that way but browning the meat first gives it a better flavor.
And the browned meat cooks much better and faster in a slow cooker or pot.