A calculated field adds a measure to a PivotTable. Its formula uses source field names rather than worksheet addresses. For example, Revenue minus Cost produces Profit. For a normal worksheet-based PivotTable, the formula operates on the summarized fields in each report group. A ratio such as Profit divided by Revenue is therefore a ratio of totals, not an average of row percentages.
The Design commands control how row fields appear. Compact form places nested labels in one column. Tabular form gives each row field its own column; Outline form separates the fields and shows group structure. You can also turn subtotals and grand totals on or off.
A formula that points at a PivotTable result can use GETPIVOTDATA. It identifies the measure and field items, so it describes the requested result instead of relying on the current report row number.