This feature is a 'magic' button that modifies column width and row height based on contents, to optimize your PowerPoint table size. The feature autofits to create the smallest height table possible (given your table's content).

PPT Productivity PowerPoint add-in's Autofit columns feature retains the width of your table but adjusts each column within that overall width based on each column's contents. Use this feature once you have finished entering data into your table.

Note - the autofit column feature was updated in May 2022 to make the feature faster and to prevent longer words breaking within a column.