The spreadsheet symbol used to convert a number to a label is

The spreadsheet symbol used to convert a number to a label is the apostrophe sign ('), also known as a single quote. When a number is preceded by an apostrophe in a cell, the cell format is automatically changed to text format, and the number is displayed as a label. This is useful when working with numbers that should not be used in calculations, such as phone numbers or product codes, and you want to make sure they are not accidentally modified by the spreadsheet program.