To show respect to the person you are referring to, in Italian it is important to use the third singular form "lei" instead of the second singular one "tu";as a consequence, all the adjectives, pronouns  and verbs will be inflected and conjugated according to this.

For instance, the phrase "I am sorry, but I disagree with your opinion." will be "Mi scusi, ma non sono d'accordo con lasua opinione." instead of "Scusami, ma non sono d'accordo con la tua opinione."

In addition to this, there are also specific words to avoid when using the formal form, such as "Ciao", which can be easily substituted with "Salve", "Buongiorno", "Buonasera",  etc...