Walking here signifies behavior in life. Alternate translation: "that you will live the way God expects you to" (See: [[rc://en/ta/man/translate/figs-metaphor]])
Paul is speaking of the Colossian believers as if they were trees or plants. As a plant grows and bears fruit, so also believers are to keep getting to know God better and doing good deeds. (See: [[rc://en/ta/man/translate/figs-metaphor]])