It is generally used with two similar data sets, totalling the numbers, retaining the most recent date, and even preserving a list of reference values.
Combine with Table – select a worksheet or a previously named table from the drop down list. The worksheet must be in the same workbook, and data must start in cell A1 with a header row. If you want to use a table in memory, use Table Name to create the reference.
Match by Row Number – select this option to combine the tables by row number. This is useful if the tables have no common columns.
Select Key Columns – select columns that will be used to align the two tables together. All values from all selected columns must match for a row to match.
Ignore case – when performing the comparison, match rows even if they have differing upper or lower case letters.
Ignore spaces – when performing the comparison, match rows even if they differ because of different spacing (leading, trailing or within the text).
Add new rows – automatically add rows that are only in the referenced table.
Add new columns – automatically add columns that are only in the referenced table.
Handling Duplicates – where both tables have matching values in the key columns, combine the values of the remaining columns using the selected options. The ‘All (list)’ option will produce a comma-separated list of values in each cell.
Blog article: Using the Combine Function