Die Gäste scheinen später zu kommen, deshalb decken wir den Tisch erst in zehn Minuten.

Die Gäste is the subject of the sentence: the guests are the ones who seem to be coming later.

A useful detail: in the plural, die can be both nominative and accusative, so the article alone does not show the case here. You know Die Gäste is the subject because of the meaning and the sentence structure.

• die Gäste = the guests

scheinen means to seem.
When it is followed by another verb, German often uses zu + infinitive.

So:

• Die Gäste scheinen später zu kommen
  = The guests seem to be coming later / The guests seem to come later

This is similar to English seem to come.

Structure:

• scheinen = the conjugated verb
• zu kommen = infinitive construction
• später modifies kommen

Because it is part of the zu-infinitive construction: zu kommen.

In German, infinitives often go to the end of the clause, especially after verbs like:

• scheinen = to seem
• versuchen = to try
• hoffen = to hope
• vergessen = to forget

So the pattern is:

• subject + conjugated verb + other elements + zu + infinitive

Here:

• Die Gäste = subject
• scheinen = conjugated verb
• später = adverb
• zu kommen = infinitive at the end

Because später here is an adverb, not an adjective before a noun.

Compare:

• später kommen = to come later
• die späten Gäste = the late guests

Adverbs do not take adjective endings in German. So:

• später = later
• not späte/späten, because those would be adjective forms

spät means late.
später is usually the comparative form, meaning later.

So:

• Die Gäste kommen spät. = The guests are coming late.
• Die Gäste kommen später. = The guests are coming later.

In this sentence, später suggests later than expected / later than some usual or planned time.

Deshalb means therefore / that is why / for that reason.

It counts as occupying the first position in the clause. In German main clauses, the conjugated verb must be in second position, so the subject comes after the verb.

That is why you get:

• deshalb decken wir den Tisch ...

and not:

• deshalb wir decken ...

This is called inversion.

Basic pattern:

• Deshalb
  • verb
    • subject
      • ...

So:

• Deshalb decken wir den Tisch erst in zehn Minuten.

Yes, but the structure changes.

1. deshalb = therefore / for that reason
   It gives the result.

• Die Gäste scheinen später zu kommen, deshalb decken wir den Tisch erst in zehn Minuten.

2. denn = because
   It gives the reason, but keeps normal main-clause word order after it.

• Wir decken den Tisch erst in zehn Minuten, denn die Gäste scheinen später zu kommen.

3. weil = because
   It introduces a subordinate clause, so the verb goes to the end.

• Wir decken den Tisch erst in zehn Minuten, weil die Gäste später zu kommen scheinen.

So the meaning is similar, but the grammar is different.

Den Tisch decken means to set the table.

It is a fixed expression:

• den Tisch = the table
• decken = literally to cover, but in this context it means to set the table with plates, cutlery, etc.

So this is not about putting a blanket over a table. It is the everyday phrase for preparing the table for a meal.

Because Tisch is the direct object of decken, so it is in the accusative case.

• nominative: der Tisch
• accusative: den Tisch

That is why the sentence has:

• wir decken den Tisch

not:

• wir decken der Tisch

Here erst means something like not until.

So:

• erst in zehn Minuten = not for another ten minutes / not until ten minutes from now

This use of erst often gives the idea of later than now, or only then.

Compare:

• Wir essen erst um acht. = We are not eating until eight.
• Ich komme erst morgen. = I am not coming until tomorrow.

So in your sentence, erst adds the idea that they will wait before setting the table.

Here it means in ten minutes, that is, ten minutes from now.

• in zehn Minuten = in ten minutes / ten minutes from now

If you want to say for ten minutes, German usually uses:

• zehn Minuten lang
• or sometimes just zehn Minuten, depending on context

Compare:

• Wir decken den Tisch in zehn Minuten. = We will set the table in ten minutes.
• Wir decken zehn Minuten lang den Tisch. = We set the table for ten minutes.

German often puts time expressions later in the clause, especially when they are not the main topic at the start.

So this word order is very natural:

• deshalb decken wir den Tisch erst in zehn Minuten

You could move parts around for emphasis, for example:

• Deshalb decken wir erst in zehn Minuten den Tisch.
• Den Tisch decken wir deshalb erst in zehn Minuten.

These are possible, but the original sentence sounds very normal and neutral.

Yes. Scheinen has two common uses:

1. to seem

   • Die Gäste scheinen später zu kommen.
   • The guests seem to be coming later.

2. to shine

   • Die Sonne scheint.
   • The sun is shining.

In your sentence, it clearly means to seem, because it is followed by zu kommen.

Yes. The comma separates two main clauses:

• Die Gäste scheinen später zu kommen
• deshalb decken wir den Tisch erst in zehn Minuten

German normally uses a comma before a connector like deshalb when it links two full clauses in this kind of sentence.

So the comma helps show the pause and the logical connection between the two parts.