V2 is the takeoff safety speed. It's the minimum speed at which the aircraft can fly, remain in control and comply with obstacle clearance requirements under 20.7.1b.
I remember in the turbo prop world some checkies would mark you down for not reducing to V2 in the second segment. This is idiotic and entirely incorrect. If you have an engine failure at a speed faster than V2, you'd maintain that to a limit. If you were slower than V2 you'd accelerate to that speed.