Once you have a Data Store containing incoming data, you can create an Analysis.
An Analysis is a drawing board for data manipulation. You can use analyses to prepare, transform, and analyze data in preexisting data stores by applying functions to selected fields.
The output of an Analysis is typically a new data store containing prepared data that is better organized and thus better suited to serve as an input for other Data Stages.
For example, if you only wanted to visualize certain data store fields from multiple incoming data stores, you could use an analysis to create a single data store comprised of those fields. You could then use that new data store to create a data view.