Data

This tab was added in Excel 2018.

Data options

This group was added in 2018 January.

Make changes to the default layout of pivot tables - Displays the "Edit Default Layout" dialog box. This lets you change your default layout options for new PivotTables.
Disable undo for large Pivot Table refresh operations to reduce refresh time - When ticked, you can select the number of rows as a threshold for when to disable it. The default is ticked.
Disable undo for PivotTables with at least this number of data source rows (in thousands) - The default is 300,000 rows.
Prefer the Excel Data Model when creating PivotTables, QueryTables and Data Connections - The Data Model integrates data from multiple tables, effectively building a relational data source inside an Excel workbook. The default it not ticked.
Disable undo for large Data Model operations - When ticked, you can select the file size (in megabytes) as a threshold for when to disable it.
Disable undo for Data Model operations when the model is at least this large (in MB) - The default is 8 Mb.
Disable automatic grouping of Date/Time columns in PivotTables - By default, date and time columns get grouped with + signs next to them. This setting will disable that default.
Enable Data Analysis add-ins: Power Pivot and 3D Maps - (Removed in 365, Added in 2016). The add-ins could be enabled here in addition to using the Add-ins tab.

Show legacy data import wizards

The new Power Query / Get & Transform Data is superior in terms of data connectors and capability compared to these legacy wizards.

From Access (Legacy) - (Added in 2018). If you want to use one of the old wizards to import your data, tick the corresponding item and then access it from the Get Data > Legacy Wizards sub menu.