Ciao, sei già a casa?

Italian often leaves out subject pronouns when they are already clear from the verb form.
Here, sei already means you are, so tu is not necessary.

You could say Ciao, tu sei già a casa?, but it usually sounds unnecessary unless you want extra emphasis, like:

• Tu sei già a casa, e lui no?

Sei is the second-person singular present tense form of essere (to be).

So:

• io sono = I am
• tu sei = you are
• lui/lei è = he/she is

In this sentence, sei is used because Italian normally uses essere to say where someone is:

• Sono a casa = I am at home
• Sei a scuola = You are at school

In standard Italian, essere is the normal verb for location in sentences like this:

• Sei a casa? = Are you at home?

You may also hear stare in some contexts, but it usually adds a slightly different idea, such as staying somewhere or emphasizing being in a place for a period of time:

• Sto a casa oggi = I’m staying home today

So for a simple question about someone’s location, essere is the most natural choice.

Già means already.

In sei già a casa?, it comes after the verb and before the place expression. That is a very natural position in Italian.

Compare:

• Sei già qui? = Are you already here?
• Hai già mangiato? = Have you already eaten?

Italian adverbs like già often go near the verb, but the exact position can vary a little depending on style and emphasis.

A casa is a fixed, very common expression meaning at home or sometimes home, depending on context.

Italian does not normally use an article here. So:

• sono a casa = I’m at home
• vado a casa = I’m going home

Using alla casa would usually mean to the house, referring to a specific house as a building, not the idea of home.

This is a very common question.

• a casa = at home / home
• in casa = in the house / indoors / inside the home

So:

• Sono a casa = I’m at home
• Sono in casa = I’m in the house

Often a casa is the more natural choice when talking about being home in the general sense. In casa focuses more on being physically inside the house.

Ciao is informal. You use it with friends, family, classmates, coworkers you know well, and other informal situations.

It would not usually be appropriate in a formal situation. For example, with someone you don’t know well, you might prefer:

• Buongiorno
• Buonasera
• Salve

So Ciao, sei già a casa? sounds natural between people who are on informal tu terms.

Usually, no. Italian often keeps the same word order as a statement and shows a question through:

• intonation in speech
• the question mark in writing
• context

So:

• Sei già a casa. = You are already at home.
• Sei già a casa? = Are you already at home?

Unlike English, Italian does not normally need a special do/are inversion rule beyond the normal verb form already being there.

To say it formally, you would normally change both the greeting and the verb form.

Informal:

• Ciao, sei già a casa?

Formal:

• Buongiorno, è già a casa?

Here, Italian uses Lei for formal you, and the verb takes the third-person singular form:

• Lei è = you are (formal)

Even if Lei is not stated, the verb è shows the formal form in context.

Già is pronounced roughly like jah.

The accent mark on à shows that the stress falls on that final syllable. In short words like this, the written accent is important.

A rough pronunciation guide for the whole sentence:

• Ciao = CHOW
• sei = sounds like say
• già = jah
• a casa = ah KAH-zah

So the whole sentence is approximately:

CHOW, say jah ah KAH-zah?