office
The Italian word 'ufficio' is used to refer to a room or a set of rooms where people work, usually seated, on tasks that involve organization, documentation, or trade. It can also refer to a position of authority within an organization. The usage in a sentence could be 'Lavoro in un ufficio' which translates to 'I work in an office'.
My office is located in the city
This is a straightforward expression relating the position of 'my office' as being located 'in the city'. In Italian, the possessive 'my' ('il mio') precedes the noun 'office' ('ufficio').
I am looking for a post office
In this sentence, the speaker is 'searching' ('sto cercando') for a 'post office' ('ufficio postale'). 'Ufficio' is used here to denote a particular type of office - a post office.
The tourist office is open today
This phrase informs us that 'the tourist office' ('l'ufficio turistico') is 'open today' ('è aperto oggi'). 'Open' in this context is 'aperto'.