This is the 38th most frequent Italian word.
stata
"Stata" is the feminine past participle of "essere," meaning "been" in English.
In this sentence, 'stata' is the feminine singular past participle of 'essere', used here in the passato prossimo tense to indicate a completed state or experience.
È stata una giornata lunga.
It has been a long day.
In this example, 'stata' is used in the trapassato prossimo tense, showing that the action happened prior to another past action.
Pensavo che fosse stata lei a lasciare la porta aperta.
I thought she had been the one to leave the door open.
Here, 'stata' functions as part of the passive voice construction, indicating an action (being built) that happened to the subject.