2 hours of walking per day is a lot of walking so yes you'll be able to lose weight walking 2 hours in a day everyday if you keep it up.
If you walk at a pace of 3 miles per hour then in 2 hours of walking you should have burned around 480 to 500 calories depending on your current weight.
If you speed up your walking pace to 4 miles per hour then you'll cover 580 to 600 calories in 2 miles of walking.