You generally pay with a credit or debit card.  Do you expect the program to explain what a credit card is?  Of course not.  The program "assumes" you know what a credit card is.  Likewise, the program should assume you know what the word "per" means.  If you don't understand that word (or any other word that the program uses), you need to use a dictionary.  The program help you prepare tax return, it is not a dictionary.