Tambarare ni kubwa.

Ni is the basic Swahili copula, meaning is / are / am.

So the structure is:

• Tambarare = the subject
• ni = is
• kubwa = big / large

That is why the sentence means The plain is big or The flat area is big, depending on the meaning you were given.

Swahili adjectives agree with the noun class of the noun they describe.

Tambarare is normally treated as a class 9/10 noun, and with many adjectives in that class, the adjective can appear with no extra visible prefix. So:

• tambarare kubwa = big plain
• Tambarare ni kubwa = The plain is big

Compare that with other noun classes:

• mtu mkubwa = big/important person
• mti mkubwa = big tree

So mkubwa is not a general form for all nouns. It is used with certain noun classes, not with tambarare here.

It is usually treated as a class 9/10 noun.

A useful thing to know about class 9/10 is that the singular and plural often look the same. So the form tambarare can potentially be singular or plural depending on context.

That noun class also helps explain why the adjective appears as kubwa.

Swahili normally does not use articles like the and a/an.

So Tambarare ni kubwa does not explicitly mark that difference. Depending on context, it could be understood as:

• the plain is big
• a plain is big
• the flat area is big

In actual use, context tells you which one is intended.

These are two different structures:

• tambarare kubwa = big plain
  
  • here the adjective directly describes the noun inside a noun phrase
• Tambarare ni kubwa = The plain is big
  
  • here you are making a full sentence

So in English terms:

• big plain = noun phrase
• The plain is big = complete sentence

That is why ni appears in the sentence version.

Not if you want to mean The plain is big in standard Swahili.

Without ni, tambarare kubwa is understood as big plain, not as a full sentence.

So:

• Tambarare ni kubwa = correct for The plain is big
• tambarare kubwa = big plain

When an adjective directly modifies a noun, it usually comes after the noun:

• tambarare kubwa = big plain

In a full sentence like this one, the pattern is:

• noun + ni + adjective

So:

• Tambarare ni kubwa = The plain is big

That is a very common and important pattern in Swahili.

A simple pronunciation guide is:

• Tambarare = tam-ba-RA-re
• ni = nee
• kubwa = KOOB-wa

A few helpful notes:

• Swahili vowels are usually pronounced clearly: a, e, i, o, u
• The stress is usually on the second-to-last syllable
• In tambarare, the stress is on RA
• In kubwa, the kw/kuw combination may feel unfamiliar at first, but with practice it becomes natural

It can be used in more than one way in Swahili, depending on context.

Very often, learners meet tambarare as a noun meaning something like:

• plain
• flat land
• level area

But related forms can also be used when talking about something being flat or level.

In Tambarare ni kubwa, though, it is functioning as the subject noun of the sentence.

Yes. With ni, the sentence is understood as a present-time statement:

• Tambarare ni kubwa = The plain is big

There is no separate word here for is being or currently is. The sentence simply gives a present description.