To hide a row/column/sheet:
Select the row, column or sheet that you want to hide.
Tap the icon.
Go to the View Menu.
Go to the Hide/Unhide option.
Choose to Hide Rows/Hide Columns or Hide Sheet.
Alternatively, you can also hide a row/column/sheet via the contextual menu.
To unhide a row/column/sheet:
Select the row or column that's adjacent to the hidden rows/columns/sheet.
Tap the icon.
Go to the View Menu.
Go to the Hide/Unhide option.
Choose to Unhide Rows/Unhide Columns.
To unhide a sheet, in the Hide/Unhide menu, from the list of Hidden Sheets, choose to unhide the sheet that you want to.
You can also unhide a row, column, or sheet via the contextual menu.