La sua carriera inizia oggi.

In Italian, possessives usually take a definite article, so sua carriera normally becomes la sua carriera.

This is one of the big differences from English:

• his career
• her career
• their career
• but in Italian: la sua carriera

A few common exceptions exist, especially with singular family members:

• mia madre
• tuo fratello
• suo padre

But carriera is not a family term, so la is expected.

Sua can mean several things depending on context:

• his
• her
• its
• your (formal your, referring to Lei)

By itself, sua does not tell you which one it is. You need context to know.

So La sua carriera inizia oggi could mean:

• His career begins today
• Her career begins today
• Your career begins today (formal)

Italian often leaves this ambiguous unless the surrounding context makes it clear.

Both iniziare and cominciare can mean to begin / to start.

So these are both natural:

• La sua carriera inizia oggi.
• La sua carriera comincia oggi.

Iniziare can sound slightly more neutral or formal in some contexts, while cominciare is also very common in everyday speech. In this sentence, either works well.

Because oggi means today, and the event is happening now or is considered current, so the present tense is the normal choice.

• inizia = begins / is beginning

Italian often uses the simple present where English might also use the present:

• Il corso inizia oggi. = The course starts today.
• La partita comincia stasera. = The match begins tonight.

So inizia oggi is completely natural.

Usually yes, especially for a professional path or long-term working life.

• carriera = career, profession-related progression, advancement

Examples:

• fare carriera = to build a career / get ahead
• una carriera politica = a political career
• una carriera musicale = a musical career

But in some contexts English career may be better translated differently. For example, if you mean a person’s general work path, Italian might sometimes prefer:

• percorso professionale
• vita professionale

Still, in your sentence, carriera is the normal and natural choice.

Yes. That is also correct.

Italian word order is flexible, so these are both fine:

• La sua carriera inizia oggi.
• Oggi inizia la sua carriera.

The difference is mainly emphasis:

• La sua carriera inizia oggi puts the topic first: her/his career
• Oggi inizia la sua carriera highlights today

Both are natural.

Yes, mostly in style.

• inizia oggi is the most straightforward and natural
• ha inizio oggi is more formal, institutional, or written

Compare:

• La sua carriera inizia oggi. = normal and natural
• La sua carriera ha inizio oggi. = more formal, a bit elevated

You might see ha inizio in announcements, official writing, speeches, or ceremonial language.

Because oggi works directly as an adverb meaning today. No preposition is needed.

• oggi = today
• domani = tomorrow
• ieri = yesterday

So:

• inizia oggi
• parte domani
• è arrivato ieri

This is similar to English, where you also say begins today, not begins on today.

You can tell from the article and the possessive:

• la = feminine singular
• sua agrees with a feminine singular noun here
• carriera is a feminine noun

So:

• la sua carriera
• not il suo carriera

Many Italian nouns ending in -a are feminine, and carriera follows that pattern.

Yes, but only if the context already makes it clear what is beginning.

Italian often omits subjects when they are understood. So if everyone already knows you are talking about the career, you could say:

• Inizia oggi.

But by itself, that just means It begins today or He/She begins today, depending on context. If you want the sentence to stand alone clearly, La sua carriera inizia oggi is better.

It is pronounced approximately kar-RYEH-ra.

A rough guide:

• car- like car
• rie sounds like ryeh
• -ra with a tapped Italian r

The stress is on the middle syllable:

• car-RIE-ra

And inizia is approximately:

• ee-NEE-tsya

So the whole sentence sounds roughly like:

• la SOO-a kar-RYEH-ra ee-NEE-tsya OD-jee

It is possible in Italian, but it is not the normal neutral order here.

The usual order is:

• la sua carriera

Putting the possessive after the noun often adds emphasis, contrast, or a special tone:

• la carriera sua = her career / his career specifically

This can sound marked or literary, and in everyday neutral Italian, la sua carriera is the better choice.

It is basically neutral.

• La sua carriera = standard structure
• inizia oggi = natural present tense
• overall tone = normal, clear, standard Italian

It could appear in many contexts:

• a speech
• a school ceremony
• a sports commentary
• a motivational sentence
• a professional announcement

So it is not especially informal, and not especially poetic either.