What is this option in Excel?

Question

excel

Somewhere I clicked something in Excel and the following tools appeared:

Why is this needed? And how to remove it?

Answer 1

"Data" tab -> then select the required columns or rows and select the "Ungroup" menu item, select "Columns" / "Rows" in the window, depending on your needs. (there is a "Group" menu item for reverse grouping)
This is used for external design, if rows / columns need to be hidden and then expanded ... the numbers show the level of nesting of such convolutions, if you click on them, it allows you to collapse / expand in whole groups. I think it's a very handy feature.