In this scene Macbeth does the deed of murdering King Duncan so he can pursue becoming the Thane Of Cawdor. There is some remnants of his guilt for doing so.
“My hands are of your color, but I shame to wear a heart so white” Said by Lady Macbeth, what she means by this is her hands are metaphorically the same as Macbeths (bloody) as she assisted with the plan of murdering Duncan, but she doesn’t fell as guilty as Macbeth for commiting the crime; Hence why she then said “I shame to wear a heart so white”