An equal sign is the first character you type when entering a formula into a cell of a spreadsheet.
For instance, if you want to find the sum of values from A1 to A4 (so we want to add up A1,A2,A3,A4) we would type [tex]=\text{SUM(A1:A4)}[/tex] into some other cell. The colon indicates we're adding cells in between A1 and A4.
