Garanția este deja plătită.

Because Romanian usually puts the definite article at the end of the noun, not in front of it.

• garanție = a guarantee / a warranty / a deposit
• garanția = the guarantee / the warranty / the deposit

So garanția means the guarantee (or whatever meaning fits the context).

This is one of the biggest differences from English: Romanian uses an enclitic definite article.

Este is the 3rd person singular of a fi (to be).

So:

• este = is

In this sentence, it links the subject to plătită and helps form a passive/resultative idea:

• Garanția este deja plătită. = The guarantee/deposit is already paid.

Because plătită agrees with garanția, which is feminine singular.

The participle/adjective changes form to match the noun:

• masculine singular: plătit
• feminine singular: plătită
• masculine plural: plătiți
• feminine plural: plătite

Since garanția is feminine singular, Romanian uses plătită.

It is originally the past participle of a plăti (to pay), but here it behaves very much like an adjective.

That is why it:

• comes after este
• agrees with the noun in gender and number
• describes the state of the noun

So in this sentence, it is part of a passive/resultative construction: is paid / has been paid.

Yes, effectively it is.

Romanian often uses a fi + past participle to express a passive meaning:

• Garanția este deja plătită. = The guarantee is already paid.

An active version would be something like:

• Cineva a plătit deja garanția. = Someone has already paid the guarantee/deposit.

So the Romanian sentence focuses on the thing paid, not on who paid it.

Deja means already, and its position is fairly natural here.

• Garanția este deja plătită. = the most neutral/common order

It comes before plătită because it modifies the whole state/result: already paid.

You may also hear:

• Garanția e deja plătită.
• Garanția este plătită deja.

The first is especially common in speech. The sentence you were given is very standard and natural.

Normally, no.

In standard Romanian, the present tense of a fi is usually expressed:

• Garanția este deja plătită.

You might see este omitted in very informal notes, headlines, or shorthand, but for normal correct sentences, keep it.

A common spoken alternative is simply the shorter form:

• Garanția e deja plătită.

Here e is just a shorter spoken form of este.

This is a very useful distinction.

• este deja plătită focuses on the current state/result: it is already paid
• a fost deja plătită points more clearly to a completed past event: it was already paid / has already been paid

In many contexts, English may translate both similarly, but Romanian makes a clearer distinction.

So if you want to emphasize the present status, este deja plătită is a very natural choice.

A rough English-friendly pronunciation is:

guh-ran-TSI-a YES-te de-ZHA pluh-ti-TUH

A few important sound notes:

• ț sounds like ts in cats
• j sounds like the s in measure
• ă sounds like the first vowel in about
• plătită has stress on -ti-
• garanția has stress on -ți-

So the rhythm is roughly:

garaNȚIa ESTE deJA plăTItă

Yes. Garanție can mean several related things, depending on the situation:

• guarantee
• warranty
• security deposit

So Garanția este deja plătită could mean:

• the warranty/guarantee is already paid for
• the deposit has already been paid

The grammar stays the same; only the real-world meaning changes with context.