Misafirler gelmeden önce annem biraz telaşlı görünüyordu.

It is made of:

• gel- = come / arrive
• -meden = without doing
• önce = before

By itself, gelmeden means without coming. But the fixed pattern -meden önce means before doing.

So misafirler gelmeden önce means before the guests arrived / before the guests came.

Turkish often uses this kind of non-finite structure where English would use a full clause.

Yes. That is completely normal in Turkish.

In this sentence:

• misafirler are the ones who come/arrive
• annem is the one who looks anxious

So even though English learners may expect before arriving to refer to the same person as the main clause, Turkish can name a different subject clearly.

Because misafirler is the subject of the time clause.

It is the one doing the action of gelmek. Subjects are normally in the basic form, often called the nominative.

Compare:

• misafirler gelmeden önce = before the guests arrived
• misafirlerden önce = before the guests

The second one is a noun phrase with önce, so it takes -den. The first one is a verb-based clause, so it uses -meden önce instead.

Because the main verb belongs to annem, not to misafirler.

The sentence has two parts:

• Misafirler gelmeden önce = time clause
• annem biraz telaşlı görünüyordu = main clause

The subject of the main clause is annem, which is singular, so the verb is singular too.

Because annem already means my mother.

It is:

• anne = mother
• -m = my

So annem = my mother.

Turkish often leaves out the separate pronoun or possessor if the meaning is already clear from the suffix.
Benim annem is also possible, but it adds emphasis, like my mother in contrast to someone else’s.

Biraz means a little, somewhat, or rather.

So biraz telaşlı means:

• a little anxious
• somewhat flustered
• a bit worried-looking

It softens the statement instead of making it sound very strong.

Telaşlı comes from:

• telaş = rush, anxiety, fluster, panic
• -lı = having, with

So telaşlı literally means having fluster/anxiety, and in natural English it can be:

• anxious
• flustered
• agitated
• hurried-looking

In this sentence, flustered or anxious fits well.

Here görünüyordu means looked or seemed.

So telaşlı görünüyordu = she looked anxious / she seemed flustered.

This is about appearance or impression, not a definite statement about her inner state.

It breaks down like this:

• görün- = appear / be seen / look
• -üyor = present continuous
• -du = past

So literally it is something like was appearing / was looking.

In smoother English, we usually say looked or seemed.

Yes.

• görmek = to see
• görünmek = to appear, to be seen, to look, to seem

They are related in form, but görünmek is its own common verb with the meaning appear / seem / look.

So in this sentence, it does not mean that someone literally saw the mother. It means she gave the impression of being anxious.

Because önce behaves like a postposition, not a preposition.

English puts words like before in front. Turkish often puts the equivalent word after the noun or clause it belongs to.

So:

• dersten önce = before class
• misafirler gelmeden önce = before the guests arrived

This word order is normal in Turkish.

Yes. Turkish word order is flexible.

You can also say:

• Annem misafirler gelmeden önce biraz telaşlı görünüyordu.

That is still natural.

The version with the time clause first puts more focus on when it happened.
The version with annem first puts the mother slightly more in the spotlight.

There is a nuance difference:

• telaşlıydı = she was anxious/flustered
• telaşlı görünüyordu = she looked/seemed anxious/flustered

So görünüyordu is a little more cautious and observational. It describes how she appeared, not necessarily what she definitely felt inside.