Harpo asks Mr.__ and Celie how to get Sofia to do what he tells her to do, because she doesn’t listen to him.
Mr.__ asks if he’s ever beat her and Harpo says no.
He asks Celie what to do and Celie tells him to beat Sofia. Celie doesn’t really think Harpo needs to make Sofia follow his orders because both of them are so happy. Celie’s probably telling Harpo to beat his wife because she’s a bit jealous.
The next time they see Harpo, he’s got a black eye. He claims that he fell off the stubborn mule, but it’s obvious Sofia hit him right back.