On the go means you’re either traveling or just zipping around being busy. If you’re catching the next flight, you’re on the go. If you’re running around all day getting ready for a birthday party, you’re on the go, too.
On the go is a phrase for people who are extremely active. If people think your rolling suitcase is a part of your body, you’re on the go a lot. When you're on the go, you have a lot of things to do, people to meet, and places to go. On the go can also refer to something you do when you’re not at home. Music you listen to on the plane is music on the go.