You don't have to brown meat before stewing the meat if you don't want too.
Browning the meat is not necessary when stewing meat but it's worth browning the meat before you do stew it though because it makes the stew and meat more flavorful.
If you want the best tasting stew with better flavor it's best to brown the meat first and then stew it.
But you can just put the meat into the stew and cook the stew without browning the meat first and the meat will cook just fine in the stew.
Browning of the meat before you stew it is the cooking process of partially cooking the surface of the meat to help remove excessive fat and to give the meat a brown color crust and flavor through various browning reactions.