You've been jawin' like a lot 'a old hens The sentence above contains an example of which literary term?

This sentence contains a "simile." A simile is a figure of speech that compares two unlike things, using "like" or "as" to show that there is a relationship. In this case, we have a person (you) being compared to "old hens." Obviously, people are not the same as hens, but the author wants you to picture in your mind that the person is chattering away ("jawin'" is western and southern slang for talking too much); and all that talking reminds the author of the sounds of squawking hens.