First of all, please notice in verse 12 God removed the gift that God alone had given Cain to be a farmer. Then we see he became both fugitive and vagabond. Both words indicate aimless wandering.
In the Hebrew fugitive is the word nûa‛ 5128 in Strong's and is a verb meaning to shake, to stagger, to wander. It refers to a displaced person, a wanderer, a vagrant. Vagabond is from the Hebrew word nûd 5110 in Strong's and is also a verb, but more emphatically has the sense of aimless motion or actions. It refers to a person moving about aimlessly without a home.
Brethren, all of mankind is on a journey, but the curse of sin to those not under the blood of Jesus Christ with eyes on Him and the goal of the Kingdom of God, is aimlessness in motion and in action on their journey.