A.T. Robertson Commentary Colossians 4:5

"Walk in wisdom toward them that are without, redeeming the time." — Colossians 4:5 (ASV)

Toward them that are without (προς τους εξω). A Pauline phrase for those outside the churches (1 Thessalonians 5:12; 1 Corinthians 5:12f.). It takes wise walking to win them to Christ.

Redeeming the time (τον καιρον εξαγοραζομενο). We all have the same time. Paul goes into the open market and buys it up by using it rightly. See the same metaphor in Eph 5:16.