Nous devons acheter une autre multiprise, parce que la rallonge ne suffit pas dans le salon.

Nous devons is the present tense of devoir for nous.

• devoir = to have to / must
• je dois
• tu dois
• il/elle/on doit
• nous devons
• vous devez
• ils/elles doivent

So Nous devons acheter... means We have to buy... or We must buy...

In everyday spoken French, people often say On doit acheter... instead of Nous devons acheter... Both are correct, but nous is a bit more formal or careful.

Because after a conjugated modal verb like devoir, the next verb usually stays in the infinitive.

So the pattern is:

• devoir + infinitive
• pouvoir + infinitive
• vouloir + infinitive

Examples:

• Nous devons acheter = We have to buy
• Je peux venir = I can come
• Elle veut partir = She wants to leave

So devons acheter is the normal structure: the first verb is conjugated, and the second stays in its base form.

In French, autre usually comes before the noun.

So:

• une autre multiprise = another power strip

Not:

• une multiprise autre

Also, autre agrees where needed with the noun:

• un autre livre
• une autre chaise
• d'autres prises

Here, multiprise is feminine singular, so une autre multiprise is correct.

These are two different electrical items:

• une multiprise = a power strip / multi-socket adapter
• une rallonge = an extension cord / extension lead

So the sentence is saying they need to buy another power strip because the extension cord is not enough.

That suggests the extension cord may reach the living room, but it does not provide enough outlets or enough practical capacity for what they need there.

This is about indefinite versus definite articles.

• une autre multiprise: not a specific previously identified one, just another power strip
• la rallonge: a specific extension cord that both speaker and listener already know about

So:

• une = a / one
• la = the

French uses articles very often, more consistently than English does.

Parce que means because and introduces the reason.

Structure:

• statement + parce que
  • reason

Here:

• Nous devons acheter une autre multiprise
• parce que la rallonge ne suffit pas dans le salon

So the second part explains why they need to buy another power strip.

You could sometimes see car for because, but parce que is more common in everyday speech.

This is the negative form of suffire.

• suffire = to be enough / to suffice
• suffit = is enough
• ne suffit pas = is not enough

The basic negation pattern is:

• ne + verb + pas

So:

• la rallonge suffit = the extension cord is enough
• la rallonge ne suffit pas = the extension cord is not enough

In spoken French, the ne is often dropped:

• La rallonge suffit pas

But in standard written French, you keep ne ... pas.

Because the subject is singular:

• la rallonge = the extension cord

Since that is singular, the verb is singular too:

• la rallonge suffit

If the subject were plural, then you would use:

• les rallonges suffisent = the extension cords are enough

It most naturally means in the living room, and it gives the context in which the extension cord is not enough.

So the idea is:

• the extension cord is not enough for the living room setup
• or it is not enough in the living room

French often places this kind of location phrase at the end.

You could think of it as attaching to the whole idea of ne suffit pas, not just mechanically to rallonge.

Yes, and the nuance would be a little different.

• dans le salon = in the living room
• pour le salon = for the living room

So:

• La rallonge ne suffit pas dans le salon focuses on the situation/location
• La rallonge ne suffit pas pour le salon sounds more like it is not sufficient for the living room's needs

Both are possible depending on what you want to emphasize.

The comma is optional here and mostly a style choice.

French punctuation can use a comma before parce que when the writer wants a small pause or clearer separation between the main idea and the explanation.

So both of these are possible:

• Nous devons acheter une autre multiprise parce que la rallonge ne suffit pas dans le salon.
• Nous devons acheter une autre multiprise, parce que la rallonge ne suffit pas dans le salon.

The version without the comma is probably more neutral.

Le salon is the standard and very common word for living room.

Depending on region or context, you might also hear:

• le séjour = living room / sitting room / main living area

But salon is extremely common and natural here.

Yes. A more conversational version might be:

• On doit acheter une autre multiprise, parce que la rallonge suffit pas dans le salon.

Or in more standard spoken French:

• On doit acheter une autre multiprise, parce que la rallonge ne suffit pas dans le salon.

Changes:

• nous → on is very common in speech
• dropping ne is also common in speech, though less formal

The original sentence is completely correct and natural, especially in careful spoken or written French.