La chiave magnetica apre sia la porta della camera sia quella dell’ascensore.

It means both ... and ....

So:

• sia la porta della camera
• sia quella dell’ascensore

= both the room door and the elevator door

In this sentence, sia ... sia ... is a pairing structure used to connect two things. It is very common in Italian.

You can often think of it as:

• sia A sia B = both A and B

Because that is how this correlative structure works in Italian:

• sia ... sia ...

You repeat sia before each item being linked.

Examples:

• Parla sia inglese sia italiano. = He/She speaks both English and Italian.
• Mi piacciono sia il caffè sia il tè. = I like both coffee and tea.

So in your sentence, Italian repeats sia before each object.

It looks the same, but here it is not functioning as a verb.

Sia can be:

1. the subjunctive of essere
2. a conjunction in the pattern sia ... sia ...

In La chiave magnetica apre sia la porta della camera sia quella dell’ascensore, it is the second case: a conjunction meaning both ... and ....

Quella means that one, but here it replaces a feminine noun already mentioned so you do not repeat it.

The full version would be:

• sia la porta della camera sia la porta dell’ascensore

To avoid repetition, Italian uses:

• sia la porta della camera sia quella dell’ascensore

So quella stands for la porta.

This is very natural Italian and sounds better than repeating la porta twice.

Because it refers to la porta, and porta is feminine singular.

Italian demonstratives must agree with the noun they replace:

• masculine singular: quello
• feminine singular: quella
• masculine plural: quelli
• feminine plural: quelle

Since porta is feminine singular, the correct form is quella.

These are contractions of di + article.

• di + la = della
• di + l’ = dell’

So:

• la porta della camera = the door of the room
• quella dell’ascensore = that of the elevator

In English, we often prefer:

• the room door
• the elevator door

But Italian commonly uses noun + di + noun/article, especially in phrases like this.

Because ascensore is masculine singular and begins with a vowel.

The article is l’ before vowel sounds:

• l’ascensore

Then:

• di + l’ascensore = dell’ascensore

The apostrophe shows the shortened article l’.

No. Italian camera usually means room, and in many contexts specifically bedroom or hotel room.

In this sentence, because we are talking about a chiave magnetica, camera most likely means hotel room.

So la porta della camera means the room door or the door to the room, not anything related to a photographic camera.

Literally, chiave magnetica means magnetic key.

In real usage, it often refers to a key card, especially in hotels.

So although the literal words are magnetic key, the natural English meaning in context is often key card.

Apre is the third-person singular present tense of aprire = to open.

So:

• la chiave magnetica apre = the magnetic key / key card opens

It matches the subject la chiave magnetica, which is singular.

Other forms:

• apro = I open
• apri = you open
• apre = he/she/it opens
• apriamo = we open
• aprite = you all open
• aprono = they open

Italian uses definite articles more often than English does.

Here, the articles help identify specific things:

• la chiave magnetica = the key card
• la porta della camera = the room door
• quella dell’ascensore = that one of the elevator

In English, you might sometimes omit an article or change the structure, but in Italian the articles are normal and expected here.

Yes, but the meaning and style change slightly.

For example:

• La chiave magnetica apre la porta della camera e quella dell’ascensore.

This is still correct and natural.

However, sia ... sia ... emphasizes that the key opens both doors. It is a bit clearer and more explicit.

So:

• e = and
• sia ... sia ... = both ... and ...

It comes after apre because it connects the two direct objects of the verb:

• apre what?
  • sia la porta della camera
  • sia quella dell’ascensore

So the structure is:

• subject: La chiave magnetica
• verb: apre
• objects: sia X sia Y

This is the most straightforward order in Italian for this sentence.