Speak For Oneself Meaning

(idiomatic) Expressing disagreement with an opinion expressed by another.

Example: Used other than as an idiom: see speak,‎ for. To provide an opinion only on one's own behalf.
  I'm here speaking for myself, not for my company.
  Speak for yourself! I think it's a great idea.
To have obvious meaning; to require no explanation.
  His fantastic record as a manager speaks for itself.
  His actions speak for themselves.