De zaal heeft zestig stoelen.

Because zaal is a de-word in Dutch. Nouns in Dutch take either de or het as their definite article, and zaal belongs to the de group.

So:

• de zaal = the hall
• een zaal = a hall

Unfortunately, whether a noun takes de or het usually has to be learned with the noun.

Zaal usually means hall, room, or auditorium, depending on context.

It often refers to a fairly large indoor space, for example:

• a lecture hall
• a theater hall
• a function room

So in De zaal heeft zestig stoelen, the idea is that the hall/room contains sixty chairs.

Heeft is the third-person singular form of hebben (to have).

The subject is de zaal, which is grammatically singular, so Dutch uses:

• ik heb
• jij hebt
• hij/zij/het heeft
• de zaal heeft

So De zaal heeft... literally means The hall has...

Dutch often uses hebben (to have) where English might prefer there is/there are, especially when talking about what a place contains.

So:

• De zaal heeft zestig stoelen.
  literally: The hall has sixty chairs.

In natural English, you might also say:

• There are sixty chairs in the hall.

Dutch can also express that idea differently, but this sentence is completely normal and natural.

Yes. That is also a very natural sentence.

Compare:

• De zaal heeft zestig stoelen. = The hall has sixty chairs.
• Er zijn zestig stoelen in de zaal. = There are sixty chairs in the hall.

Both are correct. The first focuses a bit more on the hall as the subject; the second focuses more on the existence of the chairs in that place.

Because in Dutch, numbers normally come before the noun they count, just as in English.

So:

• zestig stoelen = sixty chairs
• drie tafels = three tables
• tien boeken = ten books

That word order is completely standard.

Because zestig is more than one, so the noun must be plural.

• stoel = chair
• stoelen = chairs

Dutch often forms the plural with -en, and that is what happens here:

• stoel → stoelen

This is due to Dutch spelling rules.

In stoel, the oe already represents a long vowel sound. When the plural ending -en is added, Dutch keeps the correct vowel sound by writing:

• stoel → stoelen

The spelling does not double the vowel here.

This is just the normal plural form and is worth learning as a whole:

• singular: de stoel
• plural: de stoelen

Yes. De zaal is a single hall/room, so it is grammatically singular.

That is why the verb is singular too:

• De zaal heeft...

The number of chairs does not affect the verb, because the verb agrees with de zaal, not with stoelen.

The sentence follows the normal Dutch main-clause order:

Subject + finite verb + rest

So:

• De zaal = subject
• heeft = finite verb
• zestig stoelen = object / rest of the sentence

This is the standard pattern you will see very often in simple Dutch statements.

Grammatically, yes, but it sounds less natural in many contexts.

• De zaal heeft zestig stoelen. usually refers to a specific hall already known in the conversation.
• Een zaal heeft zestig stoelen. would mean A hall has sixty chairs, which sounds more general or unusual unless you are describing a type of hall.

So in most ordinary situations, de zaal is the more natural choice.

A rough English-friendly guide would be:

duh ZAAL hayft ZES-tikh STOE-luhn

A few notes:

• zaal has a long aa sound.
• heeft sounds roughly like hayft.
• zestig ends with a Dutch g/ch sound, which does not exist in standard English.
• stoel begins with stoe-, where oe sounds like the vowel in boot.

If you want to sound more natural, the hardest parts are usually aa, ee, and the final g in zestig.

Sometimes, yes. The best translation depends on context.

Zaal usually suggests a larger room or hall, but in some situations English might simply say room.

For example:

• in a theater: hall or auditorium
• in an event building: hall or function room
• in a hospital: sometimes ward in other contexts, though that is a different specialized use

So you should think of zaal as a large or formal room-like space, not just any small room.