Every table, column, and measure that isn't explicitly needed in the Report View should be hidden. This usually includes all relationship columns and any measure support tables and measure expressions.
If a column is rarely needed or only needed for a specific report, it can be temporarily unhidden to allow for this report to be developed and then hidden again to maximize usability. Numeric fact table columns that are referenced by DAX Measures (for example, quantity) should be hidden from the fields list, as the measures can be used for visualizing this data.
As discussed in the Parameter tables section, when all columns of a table are hidden from the Report View and at least one DAX Measure identifies the given table as its home table, a measure group icon (calculator symbol) will appear in the fields list. This clear differentiation between the measures and dimension columns (attributes) is recommended, especially if business users will be developing their own reports based on the dataset.