Views are available on most QBIS control panels.
Simply put, they provide you with a way to save complex settings to be recalled at any time simply by selecting them in a drop down list.
For example, if you have set up a task list that shows all tasks that are open and assigned to be for the current week, you can type in a name in the View panel and then click on Save. This will then save the view in your view list, in this case, the view list for tasks.
Now, whenever you look at your task list you can select this view in the drop down list and QBIS will load it up and immediately refresh your task list.
If you click on the Delete button after running a View, then QBIS will confirm if you really wish to delete it and then remove it from your list if you do.
Clicking on Default will quickly run the view that has been assigned as your default view in your profile.