What does “provided you took reasonable measures to protect your card and PIN” mean?

While there are multiple safeguards in place, as an Interac debit cardholder, you also play an important role in protecting yourself from fraud:

• Only you should use your Interac debit card or mobile device to make purchases.
• Choose a PIN that’s difficult for others to guess, avoiding obvious numbers like your telephone number or birthdate, and don’t share it with anyone. 
• Check your bank statements regularly and immediately report any unusual activity to your bank or credit union.
• If your card is lost or stolen, contact your bank or credit union right away.