Hit Unknown Combination of Keys

I somehow hit a combination of keys that caused an extra column to appear in my spreadsheet, and I can’t get it to go away. It’s on the very left of the line items, and has a - sign next to one particular line item. When I hit the - sign, it hides that line item. A + sign then appears in that column, and when I hit that, the line comes back. I have several sheets in this spreadsheet, and this extra column doesn’t show up in any of those. The top of that column has a very small 1 and a very small 2, both in boxes, instead of the normal A, B, C, etc. Please advise how I can get it back to normal. Thanks!

What you are mention it’s Menu/Data/Group & Outline, and the shortcuts are [F12] and [Ctrl+F12] to create and delete.

Group & Outline help

Thank you so much!

Please, if the answer solves the question click :heavy_check_mark:.