Braziers in Elden Ring are merely Stone Pillars that you can light up. Although interacting with just one will not do anything, lighting all the Braziers in the area can open up a previously inaccessible area. This secret area also has its own boss, who is unique from the rest of the bosses in the game. The order in which you light the Braziers does not matter, as the main goal is to light all of them.