speak up
Talk more loudly
speak for
Used other than as an idiom: see speak,‎ for.
To speak on somebody's behalf.
To claim, reserve, or occupy.
To represent an intrinsic quality
speak to
To give evidence regarding something; to attest for.
To address a particular topic.
To (figuratively) resonate with, to feel emotionally relevant to.
speak out
Talk openly and freely