"墙上凸出的托架" can be translated into English as "projecting bracket on the wall" or "wall-mounted protruding bracket".
"Projecting" emphasizes the outward extension or convexity of the bracket.
"Wall-mounted" clarifies that the bracket is attached to the wall.
"Protruding" is another adjective that can describe something sticking out, so "wall-mounted protruding bracket" is also a valid and clear expression.
Choose the one that best fits the context or your personal preference.