Sy loer deur die deur.

Because the two deurs are doing different jobs:

• the first deur is a preposition meaning through
• the second deur is a noun meaning door

So the structure is:

• Sy = she
• loer = peeks / peepes / looks sneakily
• deur = through
• die deur = the door

This repetition is completely normal in Afrikaans.

In this sentence, Sy means she.

A useful thing to know is that sy can also mean her in other contexts. For example:

• Sy loer. = She peeks.
• Ek sien sy boek. = I see her book.

So the meaning depends on the grammar of the sentence. Here, because Sy is at the start and is followed by the verb, it is the subject pronoun: she.

Loer usually means something like:

• peek
• peep
• have a sneaky look
• look secretly or briefly

It is not just the neutral verb look. It often suggests looking in a curious, cautious, or slightly secretive way.

So Sy loer deur die deur gives the idea that she is peeking through the door, not just calmly looking.

Afrikaans normally uses subject–verb–rest in a basic main clause:

• Sy = subject
• loer = verb
• deur die deur = prepositional phrase

So the sentence follows the standard pattern:

Subject + Verb + Prepositional phrase

This is very similar to English:

She peeks through the door.

Afrikaans is simpler than many languages here. Die is the normal definite article for the, regardless of gender.

So:

• die man = the man
• die vrou = the woman
• die deur = the door

Unlike languages such as German or Dutch, Afrikaans does not change the for masculine, feminine, or neuter nouns in ordinary use.

Yes, deur is a common noun meaning door.

Afrikaans nouns do not work with grammatical gender the way nouns do in languages like German or Dutch. So you do not need to learn deur as masculine or feminine for article purposes. You simply say:

• die deur = the door
• 'n deur = a door

That makes Afrikaans easier in this area.

You can tell from position and function:

• The first deur comes before a noun phrase and introduces it, so it acts as a preposition: through
• The second deur comes after die, so it is clearly a noun: door

So:

• deur die deur
  • deur = through
  • die deur = the door

This kind of thing happens in English too, just less obviously in this exact phrase.

In Afrikaans, verbs usually do not change form depending on the subject in the present tense.

So you get:

• Ek loer = I peek
• Jy loer = you peek
• Sy loer = she peeks
• Ons loer = we peek

That is much simpler than English, where you have I peek but she peeks. In Afrikaans, the verb stays loer.

Possibly, depending on context, but the most direct meaning is She peeks through the door.

The noun deur normally means door, but in real use English translations can shift a little depending on the situation. If someone is looking through an opening created by a partly open door, English might naturally say through the doorway. Still, word-for-word, deur is door.

A rough English-friendly guide is:

• Sy ≈ like say, but with a different vowel quality in real Afrikaans
• loer ≈ loor
• deur ≈ something like dare/dir with an Afrikaans vowel that does not match English exactly
• die = dee
• deur again the same as before

A few useful pronunciation notes:

• sy is not pronounced like English sigh
• die in Afrikaans is usually dee, not like English die
• eu in deur has a vowel sound that many English speakers need practice with

That would mean something different.

• deur die deur = through the door
• by die deur = at the door / by the door

So:

• Sy loer deur die deur = she is peeking through the door
• Sy loer by die deur = she is peeking at the door / by the door area

The preposition changes the meaning quite a lot here.

Normally deur means door. For gate, Afrikaans more commonly uses hek.

So usually:

• die deur = the door
• die hek = the gate

A learner should understand deur primarily as door.

You would use 'n for a/an:

• Sy loer deur 'n deur. = She peeks through a door.

Here:

• die deur = the door
• 'n deur = a door

Remember that 'n is written with a lowercase letter, even at the start of a sentence in normal spelling, though the following word is then capitalized.