Answer:
He means that Abigail is not innocent because of her false accusations against John Proctor and his wife Elizabeth.
Explanation:
From The Crucible, Abigail who was a help at the Proctor household falls in love with John Proctor and tries to seduce him. Seeing that she fails to do this, she leaves her job and begins a smear campaign against the family by first accusing Abigail Proctor of being a witch before extending her smear campaign to other members of the community.
Rev. Parris asks Abigail if her name is white and claims that Elizabeth Proctor will not sit next to something so soiled because Abigail is lying.