Il si impersonale e il verbo impersonale bisogna

Il si impersonale

The impersonal construction expresses actions, concepts, ideas that are not attributable to a specific subject but to an undetermined group of people.  Si expresses an indefinite subject, such as people or ‘a person’.

The impersonal construction is formed using si + the 3rd person singular of the verb.

In Italia si lavora dalle 9 alle 19. = In Italia le persone lavorano dalle 9 alle 19. [In Italy, people work from 9 a.m. to 7 p.m.]

NOTA BENE

The impersonal construction of reflexive verbs is formed using ci + si + the 3rd person singular of the verb.

Di solito, in vacanza ci si alza più tardi. [Usually, people get up later on vacation.]

With a verb followed by an adjective, the impersonal construction is formed by using  si + the 3rd person singular of the verb + a plural adjective.

In Italia si è aperti agli stranieri. [In Italy, people are open to foreigners.]

Se si dorme poco, si diventa nervosi. [If people sleep little,they become nervous.]

Il verbo impersonale bisogna

The verb bisogna is an impersonal verb used to express necessity or obligation, similar to “one must” or “it is necessary” in English.

It is only conjugated in the 3rd person singular, and it is followed by a verb in the infinitive.

Bisogna + infinitive

Bisogna studiare molto, per trovare un buon lavoro. [It is necessary to study a lot, to find a good position.]