if someone is all talk, they often talk about doing something brave or exciting but never do it.
He's always saying that he's going to leave and get another job but he'll never do it. He's all talk.
be all talk (and no action)
To talk a lot about something that one has not actually done or will not actually do. She may brag about donating money to the school, but I know she's all talk and no action.Oh, he's all talk—he's never worked a day in his life!
be all ˈtalk (and no action)
(disapproving) be a person who talks a lot about what they are going to do or have done without actually doing much: Don’t listen to her promises — she’s all talk and no action.