O sul fica longe.

Because sul is being used as a noun here, meaning the south. In Portuguese, cardinal directions often take a definite article when they refer to a region or direction as a thing.

So:

• o sul = the south
• o norte = the north
• o leste = the east
• o oeste = the west

This is very natural in Portuguese.

Here, fica comes from the verb ficar, and it has the sense of is located or lies rather than just stays.

So in this kind of sentence, ficar is often used to talk about location or distance:

• A praia fica longe. = The beach is far away.
• São Paulo fica no sudeste. = São Paulo is in the southeast.

In O sul fica longe, fica is the third-person singular present form, matching o sul.

Because Portuguese often uses ficar when talking about where something is located in relation to something else, especially with distance.

• Fica longe sounds natural for is far away
• É longe is also common, but usually in a more general or impersonal way:
  • É longe? = Is it far?
• Está longe can be possible in some contexts, but fica longe is especially common when describing location.

So O sul fica longe sounds more natural than O sul é longe.

It is usually treated as an adverb in this kind of sentence.

That is why it does not change form:

• O sul fica longe.
• As cidades ficam longe.

It stays longe no matter what the subject is.

Usually, no. In Portuguese, compass directions are normally written in lowercase when they are used as common nouns or directions:

• o sul
• o norte

They are capitalized only when they are part of an official name or a specific proper noun, such as:

• Região Sul
• Coreia do Sul

So in O sul fica longe, lowercase sul is standard.

A rough pronunciation guide is:

oo sool FEE-kah LON-zhee

A few notes:

• o sounds like oo here
• sul ends with a sound close to soo with a light w-like ending in many Brazilian accents
• fica has stress on fi
• longe has the zh sound, like the s in measure

A more approximate phonetic version would be:

u suw FEE-kah LON-zhee

Yes. Depending on context, sul can mean:

• the direction south
• the southern region of a country
• the South as a broad geographic area

So O sul fica longe could refer to the direction or to a southern region. Context tells you which one is meant.

The normal order here is:

O sul + fica + longe

That is the most neutral and natural order.

You could move things around in special contexts for emphasis, but for a learner, this standard order is the one to use.

Yes, very often. Ficar longe is a very common everyday way to talk about something being far away.

Examples:

• Minha casa fica longe. = My house is far away.
• O centro fica longe daqui. = Downtown is far from here.
• O sul fica longe. = The south is far away.

So this sounds natural and idiomatic.

Yes. If you want to strengthen the idea, you can say:

• O sul fica muito longe.

That means the south is very far away.

This is a very common pattern:

• longe = far
• muito longe = very far

It is a singular masculine subject.

That is why the verb is fica, not ficam.

Compare:

• O sul fica longe. = singular
• As cidades do sul ficam longe. = plural

So the verb form changes to match the subject, just like in English, but with more visible verb agreement.