This article explains additional Portfolios pages.
The Portfolio Board page shows each plan in column swim lanes. You can change your groups and choose to include/exclude additional fields on the plan cards.
The Portfolio Roadmap page lists out each plan in a roadmap timeline.
Hover over the timeline bar to view a description of the plan.
Key dates are marked on the timeline bar with diamonds. These are referred to as "timeline items" which include milestones, tasks, and so on. Hover over a timeline item to view details.