Si tens febre, no has d'anar a la feina.

Catalan often leaves out subject pronouns because the verb ending already shows who the subject is. Here, tens and has are both you (singular) forms, so tu is understood automatically.

You could say Si tu tens febre..., but that usually adds emphasis, contrast, or a special tone.

• tens is the 2nd person singular present of tenir = to have
• has is the 2nd person singular present of haver

In this sentence:

• tens febre = you have a fever
• has d'anar is part of the structure haver de + infinitive, which expresses obligation or necessity

So has here is not being used the same way as English have by itself; it is part of a verbal construction.

In Catalan, many physical states and symptoms are expressed without an article. So Catalan normally says:

• tenir febre = to have a fever
• tenir gana = to be hungry
• tenir set = to be thirsty
• tenir son = to be sleepy

An English speaker may expect something like a fever, but Catalan does not usually use una here.

It is the structure haver de + infinitive, which often means:

• to have to
• must
• should or be supposed to, depending on context

So:

• has d'anar = you have to go / you must go

In this sentence, because of no, it becomes the negative version: you should not go / you must not go / you are not to go, depending on how strongly the speaker means it.

Because de loses its final vowel before another vowel, and Catalan shows that with an apostrophe:

• de + anar → d'anar

This is very common in Catalan. Other examples are:

• d'estudiar
• l'escola
• m'agrada

So has d'anar is just the normal written form.

This is a very common question.

In a context like Si tens febre..., it is normally understood as you shouldn’t go or you mustn’t go. In other words, it is advice or prohibition.

However, negative forms with haver de can sometimes feel ambiguous to English speakers, because they may also suggest lack of obligation in some contexts.

If someone wants to be very clear, they might choose another structure:

• No hi vagis = Don’t go
• No hauries d'anar-hi = You shouldn’t go
• No cal que hi vagis = You don’t need to go

So in this sentence, context is what makes the intended meaning clear.

Because anar a means to go to, and feina is a feminine noun, so it takes la.

• anar = to go
• a la feina = to work / to the workplace

The whole phrase anar a la feina is the normal everyday way to say go to work.

Both relate to work, but they are not always used in exactly the same way.

• feina often means job, work, or workplace in everyday speech
• treball can also mean work, but often sounds more abstract, or refers to labor, work as an activity, or a piece of work

In this sentence, feina is the natural choice because anar a la feina is a very common expression for going to work.

Catalan uses the present tense after si for real or likely conditions, just like English does in sentences such as If you have a fever...

So:

• Si tens febre, no has d'anar a la feina.

is the normal pattern.

Catalan does not use the future tense after si in this kind of sentence.

Yes. Catalan has several natural ways to express the same general idea:

• Si tens febre, no vagis a la feina.
  More direct: If you have a fever, don’t go to work.

• Si tens febre, no hauries d'anar a la feina.
  Softer advice: If you have a fever, you shouldn’t go to work.

• Si tens febre, queda't a casa.
  If you have a fever, stay home.

So the original sentence is natural, but it is only one of several possible ways to say it.

A rough Central Catalan pronunciation guide is:

si tens febre, no az d'anar a la feina

A few useful points:

• h in has is silent
• si sounds like see
• anar is stressed on the last syllable: a-NAR
• feina is roughly FAY-nuh in Central Catalan
• the last vowel in febre and feina is often reduced to a weak uh sound in Central Catalan speech

Pronunciation varies by dialect, but these points will help you recognize and say the sentence.