From The Document Foundation Wiki
The Hide command allows all the rows or columns in a selected area to be hidden:
- Select the area of the sheet where you want rows and/or columns to be hidden.
- To hide rows, go to ▸ ▸ .
- To hide columns go to ▸ ▸ .
The Show command allows you to display all the rows or columns in a selected area:
- Select the area of the sheet where the rows and/or columns are hidden. You can select the whole sheet using ▸ , or by hitting Ctrl+A, or else by clicking in the empty gray square at the intersection of the headers for the rows (1,2,3...) and the columns (A, B, C...)
- To display all the rows, choose : ▸ ▸
- Similarly to display all the columns, choose ▸ ▸ .
What do you do if the first row or column is hidden?
- Select the second row or column (click in its header and keep the mouse button down).
- Drag the mouse towards the empty square in the corner.
- Release the button and go to ▸ or ▸ . The row or column reappears.