You can save, organize and reuse Flows in the 'My Flows' tab of the 'Flows' page
On the 'My Flows' tab of the 'Flows' page you will see a list of all your saved Flows. Try adding categories to your Flows as you save them, to help you organize them in the way you see fit.
The categories are shown as small buttons at the top of the page. Click on one of the buttons to see all the Flows listed in that category.
You can use your saved Flows in any other Flow by using the Link to Flow component in the Chat-editor.