So I made this left side of the rig and I want to symmetrize it to the other side but I get this result? I've been trying to fix it but couldn't get it to work. Some help would be amazing!
The symmetry operation will happen on the armature's local X axis, but you probably rotated it 90° on its Z axis in Object mode, so the local X axis is not aligned with the global orientation any more. So cancel the symmetry, apply the rotation (CtrlA) and symmetrize again.