La nuova dipendente si presenta con calma e saluta tutte le colleghe.

Italian often drops subject pronouns when the verb ending already makes the subject clear.

Here, si presenta and saluta are both third-person singular, and the subject is already stated as La nuova dipendente, so adding lei would usually be unnecessary.

So Italian prefers:

La nuova dipendente si presenta...

rather than:

La nuova dipendente lei si presenta...
which would sound redundant in normal speech.

Dipendente means employee.

It is one of those Italian nouns that often have the same singular form for masculine and feminine. So the noun itself does not change here. We know it is feminine because of the words around it:

• la = feminine singular article
• nuova = feminine singular adjective

So:

• il nuovo dipendente = the new male employee
• la nuova dipendente = the new female employee

Because adjectives in Italian usually agree in gender and number with the noun they describe.

Since dipendente is feminine singular here, the adjective must also be feminine singular:

• masculine singular: nuovo
• feminine singular: nuova
• masculine plural: nuovi
• feminine plural: nuove

So la nuova dipendente is the correct agreement.

Yes, presentarsi is a pronominal/reflexive-style verb here.

In this sentence, presentarsi means something like:

• to introduce oneself
• sometimes, depending on context, to show up / to present oneself

The si goes with the verb and is important. It is not just optional.

So:

• presentare = to present something/someone
• presentarsi = to introduce oneself / present oneself

Here, si presenta is third-person singular:

• mi presento
• ti presenti
• si presenta
• ci presentiamo
• vi presentate
• si presentano

They are related, but they do not mean the same thing.

• presenta from presentare usually means he/she presents or introduces someone/something else
• si presenta from presentarsi means he/she introduces himself/herself or presents himself/herself

Compare:

• Maria presenta il nuovo collega.
  = Maria introduces the new colleague.

• Maria si presenta ai colleghi.
  = Maria introduces herself to the colleagues.

So in your sentence, si tells you the employee is the one doing the introduction of herself.

Because con calma is a very common and natural Italian expression.

Literally it means with calm, but in English it corresponds to things like:

• calmly
• unhurriedly
• in a calm way

Italian often uses a prepositional phrase where English might prefer an adverb.

Both are possible in many contexts:

• si presenta con calma
• si presenta calmamente

But con calma often sounds more natural and idiomatic in everyday Italian.

Yes. Saluta is present indicative, third-person singular, from salutare.

Italian present tense can cover several ideas that English separates:

• she greets
• she is greeting
• sometimes even she does greet, depending on emphasis

Which one sounds best in English depends on context.

In this sentence, the present tense is simply describing what the employee does in the scene: she introduces herself and greets her colleagues.

Because everything in that phrase is feminine plural and must agree:

• tutte = all, feminine plural
• le = the, feminine plural
• colleghe = female colleagues, feminine plural

So the pattern is:

tutte + le + colleghe

Compare:

• tutti i colleghi = all the male colleagues / all the colleagues in a mixed group
• tutte le colleghe = all the female colleagues

This is a spelling rule.

Collega ends in -ga. In Italian, nouns ending in -ga usually form the plural with -ghe to keep the hard g sound.

So:

• collega → colleghe
  pronounced with a hard g, like in go

If it were written college, the pronunciation would change.

This is the same pattern as:

• amica → amiche
• bottega → botteghe

Because colleghe is specifically feminine plural, so it means female colleagues.

Italian often makes a distinction here:

• colleghi = male colleagues, or a mixed group
• colleghe = female colleagues

So this sentence tells you that the new employee greets all the female colleagues.

If the group were mixed, Italian would normally use colleghi as the default masculine plural.

In Italian, after tutto/tutta/tutti/tutte, you usually use the definite article when you mean all the ...

So:

• tutte le colleghe = all the colleagues
• tutti i libri = all the books
• tutte le persone = all the people

Without the article, it would usually sound incomplete or would belong to a different structure.

So tutte le colleghe is the normal form here.

Because both verbs share the same subject:

• si presenta
• saluta

The subject is still La nuova dipendente.

Italian, like English, does not need to repeat the subject if it is still the same person:

La nuova dipendente si presenta con calma e saluta tutte le colleghe.

This is just a coordinated structure:
[verb 1] e [verb 2] with one subject for both.