Misafirler gelmeden sürahiyi suyla dolduruverdim.

It comes from gelmek = to come.

Breakdown:

• gel- = come
• -meden = a converb ending, the vowel-harmony form of -madan/-meden

Its basic idea is without coming, but in time expressions it very often corresponds to before coming or before someone came/comes.

So here Misafirler gelmeden is understood as before the guests came.

Because -meden can already express that idea by itself in many sentences.

So both of these are natural:

• Misafirler gelmeden sürahiyi suyla dolduruverdim.
• Misafirler gelmeden önce sürahiyi suyla dolduruverdim.

Adding önce makes before more explicit, but it is not required.

Because dolmak and doldurmak are different verbs:

• dolmak = to become full
• doldurmak = to fill something, literally to make something become full

In this sentence, the speaker is doing the action to the pitcher, so Turkish uses the transitive verb doldurmak.

Compare:

• Sürahi doldu. = The pitcher became full.
• Sürahiyi doldurdum. = I filled the pitcher.

Because it is the direct object, and it is specific.

Turkish often marks a specific or definite direct object with the accusative ending. Here the form is:

• sürahi
  • -yi → sürahiyi

The y is a buffer consonant. Turkish inserts it between two vowels.

So sürahiyi means something like the pitcher or that particular pitcher as the object of the verb.

-la / -le means with or by means of.

Here:

• su = water
• su + y + la → suyla

Again, the y is a buffer consonant between vowels.

In this sentence, suyla shows what was used to fill the pitcher:

• sürahiyi suyla doldurmak = to fill the pitcher with water

-iver- / -uver- adds a nuance of doing something:

• quickly
• readily
• all at once
• almost casually
• without much fuss

So doldurdum is simply I filled it, while dolduruverdim is more like:

• I quickly filled it
• I just filled it
• I went ahead and filled it

The exact English wording depends on context, because this suffix often carries a feeling that English does not mark so neatly.

It can be broken down like this:

• doldur- = fill
• -uver- = quick / sudden / easy completion nuance
• -di = past tense
• -m = I

So:

doldur-u-ver-di-m = I filled it quickly / I just filled it

The u is part of the harmonized form of the -(I)ver- suffix.

Because Turkish often leaves subject pronouns out when the verb already shows the person.

Here the ending -m in dolduruverdim already tells you the subject is I.

So:

• dolduruverdim = I filled it quickly / just filled it

You could say Ben dolduruverdim, but that would add emphasis, contrast, or special focus.

Not of the whole sentence.

It is the subject of the subordinate part misafirler gelmeden:

• the guests are the ones who come

But in the main clause, the subject is I, shown by -m in dolduruverdim:

• I am the one who filled the pitcher

So the sentence contains two different subjects in two different clauses.

Because -meden forms a non-finite clause. Non-finite clauses in Turkish usually do not carry their own tense the way English clauses often do.

Instead, the time is understood from the main clause and the context.

Here the main verb is past:

• dolduruverdim = I filled

So gelmeden is understood relative to that past situation:

• before the guests came

In another context, the same form could refer to the future:

• Misafirler gelmeden hazır olalım. = Let’s be ready before the guests come.

Yes. Turkish word order is flexible, although the verb normally stays at the end.

This sentence uses a very natural order:

• time/background first: Misafirler gelmeden
• object and other details next: sürahiyi suyla
• main verb last: dolduruverdim

That is a neutral, smooth way to say it.

Other orders are possible for emphasis, for example if you want to highlight sürahiyi or suyla, but the original order is very standard.

Turkish has no articles like a or the, so bare nouns often rely on context.

So misafirler can mean:

• guests
• the guests
• sometimes some guests, depending on context

In this sentence, it most naturally refers to the relevant guests already understood in the situation, so English often translates it as the guests.

Yes. That is one reason learners notice this form.

Its core meaning is closely connected to without doing. Depending on context, that can be understood as either:

• without coming
• before coming

In this sentence, the time relationship makes before the guests came the natural reading:

• first, I filled the pitcher
• later, the guests came

If you want to remove almost all ambiguity, you can say:

• Misafirler gelmeden önce...

That makes the temporal meaning especially clear.