kono uekibati ha ookii.

It is read:

この うえきばち は おおきい。

In rōmaji:

Kono uekibachi wa ookii.

A few pronunciation notes:

• この = kono
• 植木鉢 = うえきばち / uekibachi
• は is written ha but pronounced wa when it is the topic particle
• 大きい = おおきい / ookii

この means this, but it must come directly before a noun.

• この 植木鉢 = this flowerpot
• これ = this one / this thing

So you can say:

• この植木鉢は大きい。 = This flowerpot is big.
• これは大きい。 = This is big.

You cannot normally say この by itself without a noun after it.

Because この is already a determiner that directly modifies a noun, like this in English.

So:

• この植木鉢 = this flowerpot

You do not say:

• このの植木鉢 ✘

The particle の is used in other kinds of noun modification, but not after この / その / あの / どの.

は marks the topic of the sentence.

So in:

この植木鉢は大きい。

the topic is この植木鉢 = this flowerpot.

A natural way to understand the structure is:

• As for this flowerpot, it is big.

This is why は is often translated as is in simple sentences, but it does not literally mean is. Its real job is to mark what the sentence is about.

This is a special feature of a few particles in Japanese.

When は is used as a particle, it is pronounced wa.

So:

• この植木鉢は is read kono uekibachi wa

But when は is part of a normal word, it is usually pronounced ha.

This spelling-pronunciation difference is very common and important to memorize.

Japanese sentences often place the main predicate at the end.

In this sentence, 大きい is the predicate, so it comes last:

• この植木鉢 = this flowerpot
• は = topic marker
• 大きい = is big / big

So the basic Japanese pattern here is:

topic + は + predicate

That is different from English, where big usually comes after is:

• English: This flowerpot is big.
• Japanese: This flowerpot, big.

There is no separate word for is in this sentence because 大きい is an い-adjective, and い-adjectives can act as predicates by themselves.

So:

• 大きい。 can mean is big

This is very different from English. In English, you need is:

• It is big.

In Japanese, with an い-adjective, you do not need だ or です for the basic plain form:

• 大きい。 = It is big.

A polite version is:

• この植木鉢は大きいです。

It is an い-adjective.

Japanese い-adjectives are adjectives, but they behave in some ways like verbs because they can end a sentence directly.

Examples:

• 大きい。 = It is big.
• 小さい。 = It is small.
• 新しい。 = It is new.

So grammatically, it is still an adjective, but it can serve as the sentence predicate without needing a separate is.

Yes, you could say:

この植木鉢が大きい。

But the nuance changes.

• は presents this flowerpot as the topic:
  As for this flowerpot, it is big.
• が tends to identify or emphasize the subject more directly:
  This flowerpot is the big one or It is this flowerpot that is big, depending on context.

In a simple neutral statement, は is very natural.
Using が is possible, but it usually feels more specific or contrastive depending on the situation.

Japanese normally does not use spaces between words.

So the sentence is normally written as:

この植木鉢は大きい。

Spaces are often added in textbooks or beginner materials to make the structure easier to see.

That means:

• beginner-style: この　植木鉢　は　大きい。
• normal writing: この植木鉢は大きい。

A common polite version is:

この植木鉢は大きいです。

This adds です after the い-adjective.

So:

• plain: この植木鉢は大きい。
• polite: この植木鉢は大きいです。

Both mean the same thing, but です makes it more polite.

They are structured differently.

1. この植木鉢は大きい。
   = This flowerpot is big.
   This is a complete sentence.

2. この大きい植木鉢
   = this big flowerpot
   This is just a noun phrase, not a complete sentence by itself.

In この大きい植木鉢, the adjective 大きい directly modifies 植木鉢.

So:

• 大きい植木鉢 = a big flowerpot
• この大きい植木鉢 = this big flowerpot

Yes, if the context is already clear.

Japanese often omits information that both speakers already understand.

So if you are already looking at the flowerpot, someone might simply say:

大きい。

That can mean:

• It’s big.
• This is big.

Japanese relies heavily on context, much more than English does.