In plain words
Through error the individual is imagined in Brahman, as a man is imagined in a wooden post. Once one knows what the false form really is, it no longer stands as a thing in its own right. Understand this.
Word for word
Understand that the individual is imagined in Brahman through error, like a person in a post. If one knows the reality of that false form, the form does not remain a real entity.