Se la presa non funziona, uso la prolunga.

Se means if. It introduces a condition:

• Se la presa non funziona = If the outlet/socket doesn’t work

This is the normal Italian way to make an if-clause.

Italian often uses the present tense for real, everyday conditions:

• Se la presa non funziona, uso la prolunga.

This has the sense of:

• If the outlet doesn’t work, I use the extension cord
• or If the outlet isn’t working, I use the extension cord

It can describe a habitual action or a simple real condition. English does something similar in sentences like If it rains, I stay home.

Italian usually omits subject pronouns when they are not needed, because the verb ending already shows who is doing the action.

• uso = I use
• usi = you use
• usa = he/she uses

So uso la prolunga already clearly means I use the extension cord.
You could say io uso la prolunga, but that adds emphasis, like I use the extension cord.

In this sentence, presa means an electrical socket, outlet, or power point depending on the variety of English.

So:

• la presa = the outlet / the socket

Be careful not to confuse it with spina, which means plug.

• presa = socket/outlet
• spina = plug

Prolunga means an extension cord, extension cable, or extension lead.

It is a feminine noun, which is why it takes la:

• la prolunga

Because both presa and prolunga are feminine singular nouns.

That means they normally take the feminine singular definite article la:

• la presa
• la prolunga

Italian uses articles more often than English, so even where English might say if an outlet doesn’t work, Italian may still naturally use la presa.

In Italian, funzionare literally means to function, but in everyday English we usually say to work for machines, devices, outlets, appliances, and so on.

So:

• La presa non funziona = The outlet doesn’t work

This is the most natural translation in English.

Yes, but the meaning changes slightly.

• La presa non funziona = The outlet doesn’t work
  This focuses on the fact that it is not functioning.
• La presa è rotta = The outlet is broken
  This says specifically that it is broken.

So non funziona is a bit broader and more neutral.

The comma separates the if-clause from the main clause:

• Se la presa non funziona, uso la prolunga.

When the condition comes first, Italian often uses a comma, just as English often does:

• If the outlet doesn’t work, I use the extension cord.

It helps readability and is very standard here.

Yes. You can also say:

• Uso la prolunga se la presa non funziona.

This means the same thing: I use the extension cord if the outlet doesn’t work.

When the se-clause comes second, the comma is often omitted.

Uso is the most natural and common choice in everyday Italian.

• uso la prolunga = normal, everyday Italian
• utilizzo la prolunga = also correct, but a bit more formal or less conversational

For most situations, uso is the better choice.

It can be understood either way, depending on context.

It may mean:

• Whenever the outlet doesn’t work, I use the extension cord
  → a general habit
• If the outlet doesn’t work, I’ll use the extension cord
  → a real situation in context

Without more context, the sentence feels very natural as a general, practical statement.

A helpful rough pronunciation is:

• funziona ≈ foon-TSYO-na

The zi here sounds like tsy.

Likewise:

• presa ≈ PREH-sa
• prolunga ≈ pro-LOON-ga

These are only rough English guides, but they help get close.

Yes. Presa can have several meanings depending on context, because it comes from the idea of a grip, hold, or point of taking/connection.

But in everyday household contexts, la presa very often means:

• socket
• electrical outlet

In this sentence, that is clearly the intended meaning because of funziona and la prolunga.

In Italian, non goes directly before the verb to make it negative.

• funziona = it works
• non funziona = it doesn’t work

This is the normal pattern in Italian:

• mangio → non mangio
• vedo → non vedo
• uso → non uso

So la presa non funziona is exactly the regular way to say the outlet doesn’t work.