In Ephesians 5, Paul speaks about how we as believers walk in the light (:8), in a world that is in darkness (:11). This age is an evil aeon and in that context Paul says that we should walk as wise men in it and redeeming the opportunity.
Ephesians 5
15 See then, brothers, how you walk diligently, not as fools but as wise,
16 redeeming the opportunity, because the days are evil.
making good use of it
The time we have here is limited (1 Cor.7:29) and elsewhere Paul says about this that the night is advancing and the day is at hand (Rom.13:12). The time and opportunity we have is precious and therefore we should make good use of it, because that is what redeeming the time means.
Ephesians and Colossians
There are many parallels between the letter from Ephesians and the letter from Colossians. These letters were written at about the same time and show many similarities. Some verses are almost identical, or through small differences between the parts of the two letters, we see that they complement each other. This is also the case with regard to what Paul says in Ephesians 5.
Colossians 4
5 Walk in wisdom toward those who are outside, making the most of the opportunity,
6 Let the word of you always be with grace, seasoned with salt, knowing how you ought to answer everyone.
the word
We should walk as wise men and also in wisdom toward those who are outside. The world is in darkness, but we may let the light of God’s Word shine. We may make use of the opportunities that we get and use the opportunities to let the light of God’s word shine.
Our word should always be in grace and knowing how we would answer everyone. Or as Peter says: Always be prepared to give an answer to anyone who asks us to give an account of the hope that is in us (1 Pet. 3:15).