Se faltar sal, você tem que comprar mais no supermercado.

Because after se meaning if, Portuguese often uses the future subjunctive when talking about a possible future situation.

So:

• Se faltar sal... = If we run out of salt / If salt is lacking...

For many -ar verbs, the future subjunctive looks exactly like the infinitive, so faltar here is not the plain infinitive in meaning, even though it looks the same.

Compare:

• Falta sal. = There is no salt / Salt is missing.
• Se faltar sal... = If salt runs out / If there isn’t enough salt...

This is a very common pattern in Portuguese:

• Se chover... = If it rains...
• Se precisar... = If you need to...
• Se der tempo... = If there is time...

Here, faltar means something like:

• to be missing
• to be lacking
• to run out

So faltar sal is literally for salt to be lacking, but in natural English it usually becomes:

• if we run out of salt
• if there isn’t enough salt
• if salt is missing

A helpful thing to remember is that faltar often works differently from English. The thing that is missing becomes the grammatical subject:

• Falta sal. = Salt is missing / We need salt.
• Faltam duas cadeiras. = Two chairs are missing.

Because sal here is being used as an uncountable substance in a general sense, like salt in English.

So:

• faltar sal = to be short of salt / to run out of salt

If you say o sal, it sounds more like a specific salt you already have in mind:

• Faltou o sal da receita. = The salt for the recipe was missing.
• Acabou o sal. = The salt is gone / We ran out of the salt.

In everyday speech, both article and no article can appear depending on nuance, but faltar sal is very natural when talking about needing more of a substance.

No. ter que + infinitive is a very common way to say have to in Portuguese.

So:

• você tem que comprar = you have to buy

This is one of the standard ways to express obligation.

Common alternatives are:

• você tem de comprar
• você precisa comprar

All of these can mean you need to buy / you have to buy.

In everyday Brazilian Portuguese, ter que is extremely common and natural.

In most everyday Brazilian Portuguese, the difference is small, and both usually mean have to.

• tem que comprar = very common, conversational
• tem de comprar = also correct, sometimes a bit more formal or less common in casual Brazilian speech

In practice, learners should understand both. If you use tem que, you will sound very natural in Brazil.

Here mais means more.

The full idea is:

• comprar mais = buy more
• more of what? salt

Portuguese often leaves out the noun when it is obvious from context.

So the sentence does not need to repeat sal:

• Se faltar sal, você tem que comprar mais...
• literally: If salt is lacking, you have to buy more...
• naturally: If we run out of salt, you have to buy more...

It could. That would also be correct:

• Se faltar sal, você tem que comprar mais sal no supermercado.

But Portuguese often omits words that are already clear from the context. Since sal was just mentioned, mais by itself is enough.

This is very normal and natural.

Compare in English:

• We need milk. Can you buy more? You do not need to say more milk if it is already obvious.

No is a contraction of:

• em + o = no

So:

• no supermercado = in the supermarket or at the supermarket

In this sentence, the most natural English translation is usually:

• at the supermarket

This kind of contraction is extremely common in Portuguese:

• na loja = in/at the store (em + a)
• nos mercados = in/at the markets (em + os)
• nas farmácias = in/at the pharmacies (em + as)

Because comprar no supermercado focuses on the place where you buy something: at/in the supermarket.

• comprar no supermercado = to buy at the supermarket

If you say ir ao supermercado, that means to go to the supermarket:

• Você vai ao supermercado. = You go to the supermarket.

So:

• ao supermercado is common with movement verbs like ir, levar, chegar in certain contexts
• no supermercado is common when talking about where something happens

Yes, it could often be omitted, but keeping it is very natural.

Portuguese often drops subject pronouns when the verb ending already shows who the subject is. But with você, the verb uses the same form as ele/ela, so the pronoun is often included for clarity.

So both are possible:

• Se faltar sal, você tem que comprar mais no supermercado.
• Se faltar sal, tem que comprar mais no supermercado.

The version with você is clearer because it explicitly says you.

No, not in this context.

Although faltar can sometimes relate to absence or missing, faltar sal does not mean to miss salt emotionally. It means salt is lacking or we run out of salt.

For emotional to miss someone/something, Portuguese usually uses sentir falta de:

• Sinto falta de você. = I miss you.

So:

• faltar sal = salt is lacking
• sentir falta de sal would be unusual unless you mean something like to miss the taste/presence of salt

Yes. It can be interpreted a little broadly.

Depending on context, faltar sal can suggest:

• there is none left
• there is not enough
• more is needed

So it can cover both:

• if we run out of salt
• if we’re short on salt

That flexibility is normal.

Yes, and it is very common.

• Se faltar sal... = If salt is lacking / If we run out of salt...
• Se acabar o sal... = If the salt runs out / If the salt is finished...

Acabar often sounds a bit more directly like to run out, while faltar can sound a little broader, like to be missing / to be insufficient.

Both are natural, but the nuance is slightly different.

Because after se for a future condition, Portuguese normally does not use the future with vai the way English uses will.

Instead, Portuguese uses the future subjunctive:

• Se faltar sal... = If salt runs out...

This is one of the biggest differences from English. Portuguese usually avoids structures like if it will... in this kind of sentence.

More examples:

• Se chover, ficamos em casa. = If it rains, we stay home.
• Se você puder, me ligue. = If you can, call me.

With você, it is specifically directed at you.

• você tem que comprar = you have to buy

But depending on tone and context, você in Brazilian Portuguese can sometimes sound more general, like English you in you have to... meaning one has to... Still, in most everyday situations, this sentence would be understood as speaking to one person directly.

If you wanted a more general statement, you might say something like:

• Se faltar sal, tem que comprar mais no supermercado.
• Se faltar sal, é preciso comprar mais no supermercado.

Sometimes, yes, but have to is usually the better match here.

• tem que = usually have to / need to
• must in English can sound stronger, more formal, or more absolute

So:

• você tem que comprar mais = you have to buy more
• you must buy more is possible, but often sounds a bit stronger than the Portuguese original

It breaks down like this:

• Se faltar sal = If salt is lacking / If we run out of salt
• você tem que comprar mais = you have to buy more
• no supermercado = at the supermarket

So the pattern is:

• Se + future subjunctive, main clause

This is a very common Portuguese conditional pattern for real future possibilities:

• Se precisar, me avise. = If you need to, let me know.
• Se sobrar comida, guardamos. = If there is food left over, we save it.
• Se faltar dinheiro, eu ajudo. = If money is lacking / If we don’t have enough money, I’ll help.