Paul is describing the Colossians as though Jesus had physically washed them, put them in clean clothes, and brought them to stand before God the Father. (See: [[rc://en/ta/man/translate/figs-metaphor]])
Paul uses two concepts, "blameless" and "above reproach," that mean almost the same thing to emphasize the idea of perfection. Alternate translation: "holy and perfect" (See: [[rc://en/ta/man/translate/figs-doublet]])