Vision is the map/outline/blueprint, that will show path to you and your team towards the ultimate goal. The product owner establishes this before any work begins.
The vision of a project tells you, your team, everyone really, where you're going and what valuable product or enhancement you'll deliver at the end.
The destination contained within the vision is what we call a Minimum Viable Product, or MVP.
The MVP is about developing a product just enough to get it out the door to early adopters. Who can then provide feedback for product improvment. This approach is basically saying, that if we do a small set of work to get our usable product out the door, we've met the goal. There are a couple of good reasons for approaching the work this way.
The first level of decomposition or the initial step in setting a project vision is to identify your themes. Themes are just a broad grouping of similar work. So, carefully group the similar tasks.
Restaurants do this every day. Appetizers, Salads, Entrees, and Dessert are the themes they work with. These aren't simply to attract or help customers read the menu. They're also useful in organizing the kitchen. The same is true for your themes.
Considering an example of a Mobile App for customers to order lunch, our app themes might be: profile, order, payment, and delivery, among others.
These themes help us in two ways. First, they help trigger ideas about what needs to be developed to meet the MVP for that theme. Second, they help us group our work together so we can be efficient and minimize risk, like ensuring we have security built before we complete the profile development.
Once we've identified our themes, we break them down further into features. Features are the next smaller slice of work we can use to help us stay organized. For example: a good Profile has a user picture, details. Hence you would, require a feature of user uploading their pictures and their other details, to be displayed on their Profile.