Not to mince one's words / To be outspoken
Literally 'not to have hairs on the tongue'. Describes someone who says exactly what they think, without softening or filtering their words.
My grandmother doesn't mince her words, she says what she thinks.
I'm telling you because I don't mince my words: that plan isn't going to work.
—What did she tell you? —Without mincing her words, that I was doing it wrong.