A hierarchy gives a visual an ordered path through detail: Year, Quarter, then Month. You can start at Year and use the drill controls above the selected visual. Go to next level replaces the current labels with the next level. Expand all down one level keeps the parents, so Q1 in 2024 stays separate from Q1 in 2025.
Drill down into a data point when you want one branch, such as the months within 2025. Drill up returns to the parent. The distinction matters most with repeated labels. A chart of Month alone combines January from every year unless another filter separates them. Use the complete Date table rather than the fact date: it supplies periods that had no orders and keeps the hierarchy consistent across measures.