I think this scene says that lady Macbeth thinks that Macbeth is to scared to kill the king. there for she wanted to kill the king to become queen .

she  asks the witches to take away  her  feminine side to  fade away so she has enough power to kill him so she can        become rich and powerful.

I think that Macbeth is joyful of the witches saying he will become king but he is also curious how he will do it.

‘ come to my women’s breast and take my gal