What does sanctifying one's work mean?

It means working like Jesus Christ – working hard and well, honestly and fairly, in order to love and serve God and other people. People who do that are making their work holy, and helping to sanctify the world from the inside. They are making the Gospel present in all their activities, whether brilliant or humble and hidden. In God’s eyes, what matters is the love people put into their work, not its success in terms of money or fame.