Si plou, no quedarem a la plaça; tornarem a casa.

Si means if.

Catalan makes an important spelling distinction:

• si = if
• sí = yes

So in this sentence, Si plou means If it rains. The version with an accent, sí, would be wrong here.

After si meaning if, Catalan normally uses the present indicative for a real future possibility:

• Si plou... = If it rains...

This works much like English, where we say If it rains, we’ll go home, not normally If it will rain...

So the pattern is:

• si + present
• main clause in future if the result is in the future

That is exactly what you have here:

• Si plou
• no quedarem...; tornarem...

Catalan does not use a dummy subject like English it with weather verbs.

So:

• English: it rains
• Catalan: plou

The verb plou by itself already means it is raining / it rains. You do not add a subject pronoun.

The same happens with other weather expressions, for example:

• Neva = It is snowing
• Fa fred = It is cold

Because they describe what we will do if the condition happens.

Both forms are 1st person plural future:

• quedarem = we will ...
• tornarem = we will return / go back

So the tense pattern is:

• condition: Si plou
• future result: no quedarem...; tornarem...

This is a very common Catalan structure.

Catalan often leaves out subject pronouns because the verb ending already shows who the subject is.

Here:

• quedarem
• tornarem

both already tell you the subject is we.

So nosaltres is unnecessary unless you want extra emphasis or contrast.

For example:

• Si plou, no quedarem a la plaça.
• Si plou, nosaltres no quedarem a la plaça, però ells sí.

In the second sentence, nosaltres is used for emphasis or contrast.

This is about the difference between quedar and quedar-se.

In Catalan, adding the reflexive pronoun can change the meaning:

• quedar = often to meet, to arrange, or sometimes to remain
• quedar-se = to stay

So quedarem and ens quedarem are not automatically the same thing.

If you wanted the clear meaning we will stay, Catalan often uses:

• ens quedarem

Without ens, the verb is the non-reflexive quedar, which can have a different meaning depending on context.

That is the normal position for basic negation in Catalan.

Pattern:

• no + verb

So:

• no quedarem = we will not ...

This is standard Catalan word order. If there were pronouns, they would usually come between no and the verb:

• no ens quedarem
• no hi anirem

Because plaça is a feminine noun, so it takes la:

• la plaça

The contraction al only happens with:

• a + el = al

For example:

• al parc = to the park

But with feminine la, there is no contraction:

• a la plaça

So al plaça is incorrect.

A casa is a very common fixed expression meaning home or to home / at home, and it usually appears without an article.

So:

• tornarem a casa = we’ll go back home

This is similar to how English says go home, not go to the home.

But if you mean a specific house, Catalan can use an article:

• a la casa dels avis = to the grandparents’ house

So a casa is the idiomatic form when the meaning is simply home.

Because Si plou is an introductory conditional clause.

When the if-clause comes first, Catalan normally separates it from the main clause with a comma:

• Si plou, no quedarem...

This is very similar to English punctuation:

• If it rains, we won’t...

If the order is reversed, the comma is often omitted:

• No quedarem a la plaça si plou.

The semicolon links two closely related main clauses:

• no quedarem a la plaça
• tornarem a casa

Both are results of the same condition, Si plou.

The semicolon shows a stronger break than a comma, but not as strong as a full stop. It helps keep the sentence clear.

You could also write this in other ways, for example:

• Si plou, no quedarem a la plaça i tornarem a casa.
• Si plou, no quedarem a la plaça. Tornarem a casa.

The semicolon is just a stylistic punctuation choice.

Yes. Catalan allows some flexibility.

For example, you could say:

• No quedarem a la plaça si plou; tornarem a casa.

That still means basically the same thing.

Putting Si plou first is very natural because it introduces the condition right away. It helps the listener understand the situation before hearing the result.

So the original order is common and clear, but it is not the only possible one.

It is a real conditional sentence: a possible condition and its likely result.

Structure:

• Si + present indicative
• main clause in the future

So here:

• Si plou = condition
• no quedarem a la plaça; tornarem a casa = result

This is one of the most useful basic Catalan patterns for talking about future possibilities.