Oggi inizia la primavera

Pronome relativo CUI
Relative pronoun CUI

“gli unici due giorni dell’anno in cui…”
(the only two days of the year in which…)

“Cui” is a relative pronoun in Italian that is used to introduce a subordinate clause and to refer to a noun or a pronoun that comes before it.
It is used instead of “che” (that, which) when following a preposition.
For example, in the sentence above, in cui means when, in which in English, referring to the noun giorni (days) that was previously mentioned.

Here are more examples:

– Nella città IN CUI abito ci sono molti cinema (There are a lot of cinemas in the town in which I live)
– Questo è un problema SU CUI dobbiamo riflettere (This is a problem on which we need to reflect)
– Sai il motivo PER CUI ti ho chiamato? (Do you know the reason for which I called you?)