Genesis 2:6 (ESV)

6 and a mist was going up from the land and was watering the whole face of the ground

It is important to note that Genesis 2:6–7 connect to Genesis 2:5. They show that the Lord made sure that the cultivation of the earth could begin. The ground received moisture and God created man. Those are the two conditions to begin arable farming. The Lord ensured that those conditions were met.

The Lord caused the ground to be moistened. The word translated here as mist can have different meanings. Whatever the exact meaning may be, God made sure, even before it rains, that the ground was moist enough to be able to cultivate it.