Kinds of visions:
Dreams - Visions that come to one while asleep. Often highly symbolic.
Inner Vision - A deep inner impressions, often accompanied with snap shot images that pass through the mind.
Open Heavens Vision - A vision or snap shot that appears to be appearing right in front of the visionary.
Spiritual Vision In Translation - A vision received while one's spirit is translated in spirit to another time, place, or spiritual plane.
Visions can reveal details about God, Heaven, the enemy, people, nations, communities, places, etc. The details can be from the past, the present, or the future.
Visions often employ one or all of the five senses (sight, hearing, touch, feeling, smell).
Acts 2:17
And it shall come to pass in the last days, saith God, I will pour out of my Spirit upon all flesh: and your sons and your daughters shall prophesy, and your young men shall see visions, and your old men shall dream dreams: