Answer:
"Keeping faith," means to be true, consistent and honest with one's words or promises.
Machiavelli's advice is to his followers is that princes should break their promises if it's no longer in their favour to keep it or if events change. He also advised that they lied about the reason why the faith was broken.
He stated that a ruler should always tell people what they want to hear regardless of how true or false it is.
Liverotto is an example of a prince who sized political power via unscrupulous means. After serving in the Army, he returns home and sized power by slaughtering the powerful men under his uncle in the guise that he had come to impress them with the army.
Cheers!