Thy steps shall not be straitened; thou shalt manage thine affairs with great facility, and safety, and success. It is a metaphor from those who walk in a strait and uneven path, where they are apt to stumble and fall. Not stumble; not miscarry.
Related Commentaries of Proverbs 4:12
Proverbs 4:12
12 When thou goest, thy steps shall not be straitened; and when thou runnest, thou shalt not stumble.