Silence means consent.
This saying encourages people to speak out if they disagree.

She doesn’t mince her words.  Mincing meat makes it easier to swallow.

I operate my mouth before engaging my brain.   I overheard this remark.  If everyone stopped to think before they spoke a lot of hurts could be avoided.

Set a guard over my mouth Psalm 141:3  I tend to think of guard in the sense of an object, but the reference is more likely to be a being like a guardian angel.  A gum-shield used in certain sports would not have  the same effect!

She’s very guarded.  She is careful what she says – possibly reluctant to reveal facts or opinions.

To become expansive means to open up and talk frankly.

Talking turkey is an American expression meaning talking frankly or getting down to business.  (Oxford Dictionary of Modern Slang).  A talking turkey would be something quite different!

If you can’t say something kind, don’t say anything.
This is a good principle to live by.

Don’t stick your oar in where it’s not wanted.
This saying recommends resisting the temptation to give advice or interfere in situations, which do not really concern you.

He has a lot to answer for.
This use of answer means take responsibility or the blame for.  If he were on trial he would be able to answer.

Don’t put the words into my mouth! means “Don’t tell me what to say!”

Put the words into someone’s mouth 2 Samuel 14:19 gives an example of the use of this expression.  The whole chapter is about the use of speech to influence someone in a position of power.