Rename sheets
To rename an existing sheet, tap the current sheet tab once so that the pop-up menu appears, then tap the Rename option. In the Sheet Name window that opens, enter the desired sheet name and tap OK.

Hide/Unhide sheets
If you have a lot of sheets, you can hide some of them you don't need for the moment to facilitate the work. To do that, tap the current sheet tab once to access the pop-up menu with the More -> Hide option, then tap it.
To display a hidden sheet, tap the current sheet tab once or double-tap an inactive tab so that the pop-up menu appears, then tap the More -> Show option, and select the sheet you want to unhide.

Duplicate sheets
To duplicate an existing sheet, tap the current sheet tab once to access the pop-up menu with the More -> Duplicate option, then tap it.