Explanation:

Box 1: User
Type of dashboard: If you want your dashboards to be available across the organization and do not want to manage the access levels at a more detailed level, you might want to create an organization-owned dashboard.
However, if you are concerned about the access privileges and security of your dashboard, consider creating a user-owned dashboard where you have more control on who can access it.
Box 2: Single-stream
The single-stream dashboards display real-time data over one stream based on an entity view or queue. The single-stream dashboards are typically helpful to Tier 2 service leads or managers, who monitor fewer, but more complex or escalated cases.
Reference:
https://docs.microsoft.com/en-us/powerapps/developer/model-driven-apps/create-dashboard
https://docs.microsoft.com/en-us/powerapps/maker/model-driven-apps/configure-interactive-experience-dashboa