Sy bel die polisie.

No. Sy can also mean his in other contexts.
In this sentence, it means she because it comes before the verb bel and is clearly being used as the subject.

• Sy bel ... = She calls ...
• sy motor = his car

So context tells you which meaning is intended.

Bel means call in the sense of phone/call by telephone. It is a very common Afrikaans verb.

So Sy bel die polisie means that she is calling the police, usually by phone.

Afrikaans verbs usually do not change form depending on the subject the way English verbs do.

In English:

• I call
• she calls

In Afrikaans:

• ek bel
• sy bel

So the verb stays bel.

It can mean either, depending on context. Afrikaans often uses the simple present where English might use either the simple present or the present continuous.

So Sy bel die polisie can mean:

• She calls the police
• She is calling the police

The situation usually makes it clear.

Die is the Afrikaans definite article, meaning the.

A very useful thing for learners is that die does not change for gender or number. Afrikaans does not have different forms like the for masculine/feminine/neuter nouns.

So:

• die man = the man
• die vrou = the woman
• die kinders = the children

Here, die polisie means the police.

Usually die polisie means the police as an institution or the police force in general, not one individual officer.

If you want to refer to one police officer, you would normally use something like:

• die polisieman = the policeman
• die polisiebeampte = the police officer

So in this sentence, die polisie is best understood as the police.

Yes. This is a basic main clause with normal word order:

• Sy = subject
• bel = verb
• die polisie = object

So it follows the same basic pattern as English: subject + verb + object.

No. Afrikaans die is pronounced roughly like dee, not like English die.

A rough pronunciation guide for the whole sentence is:

• Sy ≈ say
• bel ≈ bell
• die ≈ dee
• polisie ≈ po-lee-SEE

These are only rough English approximations, but they are helpful for beginners.

Afrikaans usually uses a double nie in negative sentences.

So:

• Sy bel die polisie.
  becomes
• Sy bel nie die polisie nie.

This is a very common Afrikaans pattern:

• first nie comes after the verb
• second nie comes at the end of the clause

Normally, you would say die polisie here. The article die is the standard choice when talking about the police.

So Sy bel die polisie is the natural, standard sentence.

Leaving out die would sound incomplete or unnatural in most normal contexts.