I am the new tenant on the third floor.
in-kwi-LEE-no — four syllables; stress the third; 'qu' is a 'kw' cluster.
Use this when introducing yourself after moving into an Italian apartment building. It is considered polite (and practically useful) to introduce yourself to immediate neighbours within the first few days of moving in.
Inquilino means tenant/occupant. Introducing yourself establishes social goodwill and gives neighbours context for any inevitable sounds from your flat. In Italian buildings where walls and ceilings transmit sound easily, good neighbour relations are practically important. Bringing a small gift (a bottle of wine or a box of chocolates) on first introduction is appreciated.
Ci siamo appena trasferiti qui.
We have just moved in here.
Plural form for couples or families; trasferirsi means to relocate/move.
Abito al secondo piano, appartamento quattro.
I live on the second floor, apartment four.
More specific self-identification; useful if the building has many flats.
Piacere di conoscerla, sono Marco.
Pleased to meet you, I am Marco.
Formal introduction; conoscerla (to meet you — formal Lei form) shows respect.
The tradition of portare un dono (bringing a gift) when meeting new neighbours dates to ancient Italian hospitality customs. In modern Italian condominiums, it is a powerful social signal that you value good relations. The gift need not be elaborate — a box of biscotti, a bottle of local wine, or a jar of honey from a weekend trip all work beautifully. This small investment in goodwill pays dividends throughout your tenancy.