Jednotlivé pokoje jsou malé.

Because it is the nominative plural form of pokoj (room).

• singular: pokoj
• plural: pokoje

In this sentence, the subject is plural, so Czech uses the plural noun form.

Jsou is the 3rd person plural form of být (to be), so it means are.

Because pokoje is plural, the verb also has to be plural:

• pokoj je malý = the room is small
• pokoje jsou malé = the rooms are small

So this is normal subject-verb agreement.

Because both words are adjectives describing pokoje, and adjectives in Czech must agree with the noun they describe.

Here, pokoje is:

• masculine inanimate
• plural
• nominative (because it is the subject)

So the adjectives also take the matching ending:

• jednotlivý → jednotlivé
• malý → malé

This is one of the most important patterns in Czech: adjectives change their endings depending on the noun.

Because pokoje is masculine inanimate, not masculine animate.

In the nominative plural:

• masculine animate adjectives often end in -í
• masculine inanimate adjectives often end in -é

Compare:

• malí chlapci = small boys (masculine animate)
• malé pokoje = small rooms (masculine inanimate)

So malé is correct because rooms are not animate.

Jednotlivé means something like:

• individual
• separate
• particular
• sometimes each separate

So Jednotlivé pokoje jsou malé suggests the individual rooms are small or the rooms are small when considered one by one.

It is a bit more specific than just Pokoje jsou malé.

• Pokoje jsou malé. = The rooms are small.
• Jednotlivé pokoje jsou malé. = The individual/separate rooms are small.

Not exactly.

• všechny pokoje = all the rooms
• jednotlivé pokoje = the individual rooms / separate rooms

Všechny pokoje emphasizes the whole group. Jednotlivé pokoje emphasizes the rooms one by one.

Sometimes the difference is small in context, but the nuance is different.

Yes. You can say:

Pokoje jsou malé.

That is a simpler sentence meaning The rooms are small.

Adding jednotlivé gives extra nuance, but it is not required for the grammar of the sentence.

No, Czech word order is fairly flexible.

The neutral order here is:

Jednotlivé pokoje jsou malé.

But other orders are possible, depending on emphasis, for example:

• Pokoje jsou malé.
• Malé jsou jednotlivé pokoje.
  • marked, more literary or contrastive
• Jednotlivé jsou malé pokoje.
  • much less natural in ordinary speech

So the given order is the most straightforward and natural one.

Normally, no. In a regular present-tense sentence like this, Czech keeps the verb:

• Pokoje jsou malé.

Czech often drops subject pronouns, but not the verb itself:

• Jsou malé. = They are small.
  (subject pronoun omitted, but jsou stays)

Leaving out jsou would sound incomplete in normal standard prose, except in headlines, notes, or very special styles.

The singular would be:

Jednotlivý pokoj je malý.

Notice how everything changes to singular:

• jednotlivé → jednotlivý
• pokoje → pokoj
• jsou → je
• malé → malý

This is a good example of how Czech marks number across the whole sentence.

Great question: -é is not uniquely plural by itself.

You identify it from the whole sentence:

• pokoje is clearly plural
• jsou is plural
• therefore jednotlivé and malé must also be plural forms agreeing with pokoje

So in Czech, you often understand a form not from one word alone, but from how all the words fit together.