It’s a low-impact type of exercise, so it’s easier on your joints than running or other high-impact aerobic activities. But it still helps you get into shape.
The best way to build your cardiovascular fitness on the bike is to ride for at least 150 minutes every week. For example, you could cycle to work a few days a week, or do a couple of shorter rides during the week with a longer ride at the weekend. You’ll soon feel the benefits.