These are simply purchases1 you make using your Citibank debit card. When doing so, you usually have the option to press either the Debit or the Credit button. When you press Credit, your signature is required; when you press Debit, you’re asked for your PIN (which is the code you enter at ATMs). The Points you get in each case vary:

For each purchase that requires your signature, you get 1 point for every $2 you spend
For each purchase that requires you to enter your PIN, you get 1 point for every $3 you spend
Did you know... Since you get more Points for signature-based transactions, always press Credit if you get the choice.2

You can sign on to your account at Citi.com to estimate your monthly debit card purchases.