You can include both variable string fields and constant hard-coded text strings in formulas. To indicate that text you enter in the formula should be treated as a hard-coded string, enclose the text in double-quotation marks. (" ")

Example:
If you would like to display the strings True or False, when comparing the Department Name for a user
If (DepartmentName="Company","True","False")
Here Company, True, False are all hard coded text strings and hence they need to be entered with double-quotation marks.