Explanation:

Box 1: FactEvents
Fact tables store observations or events, and can be sales orders, stock balances, exchange rates, temperatures, etc.
Box 2: DimChannel
Dimension tables describe business entities - the things you model. Entities can include products, people, places, and concepts including time itself. The most consistent table you'll find in a star schema is a date dimension table. A dimension table contains a key column (or columns) that acts as a unique identifier, and descriptive columns.
Box 3: DimEvent
Reference:
https://docs.microsoft.com/en-us/power-bi/guidance/star-schema