kaiyakukin ha takai.

It is read かいやくきん.

• 解約 = cancellation, termination of a contract
• 金 = money, fee, charge

So 解約金 is a compound noun meaning a cancellation fee, termination fee, or penalty fee.

は marks the topic of the sentence.

So 解約金は高い。 is literally closer to:

• As for the cancellation fee, it is high.

In natural English, this is often just translated as:

• The cancellation fee is high.

A very common beginner mistake is to think は always means is. It does not. It marks what the sentence is talking about.

In Japanese, 高い is an い-adjective, and い-adjectives can act as the predicate by themselves.

So:

• 解約金は高い。 = complete sentence

There is no missing verb here. Japanese does not need a separate is in this kind of sentence.

This is different from English, where you need is:

• The cancellation fee is high.

But in Japanese, 高い already does that job.

Yes. 解約金は高いです。 is the polite version.

• 解約金は高い。 = plain / casual / neutral written style
• 解約金は高いです。 = polite

Both are grammatically correct. Which one you use depends on the situation.

高い can mean several related things, including:

• high
• expensive
• costly

With prices, fees, and charges, 高い usually means that the amount is high, so in natural English it often becomes:

• The cancellation fee is high
• The cancellation fee is expensive
• The cancellation fee costs a lot

So even though the core meaning is high, the practical meaning here is about cost.

Yes, you could also say 解約金が高い。, but the nuance changes.

• 解約金は高い。 = As for the cancellation fee, it is high.
• 解約金が高い。 = The cancellation fee is the thing that is high / It’s the cancellation fee that is high.

Very roughly:

• は = topic, contrast, general statement
• が = more focus on the subject itself

In many contexts, は sounds more natural for a general comment.
が might be used when identifying what exactly is high.

For example:

• 基本料金は安いけど、解約金が高い。 = The basic monthly fee is cheap, but the cancellation fee is high.

Yes, but only in a normal Japanese way.

The sentence does not explicitly say:

• whose cancellation fee
• what contract or service this is about
• compared to what it is high

Japanese often leaves out information that is understood from context.

So 解約金は高い。 could mean things like:

• The cancellation fee is high.
• Their cancellation fee is high.
• This plan’s cancellation fee is high.

The exact meaning depends on the situation.

It can mean either one, depending on context.

Japanese nouns usually do not show singular vs. plural the way English does.
So 解約金 could refer to:

• a specific cancellation fee
• cancellation fees in general

Context tells you which is meant.

For example:

• talking about one phone plan: The cancellation fee is high
• talking about contracts in general: Cancellation fees are high

You are right: normal Japanese is usually written without spaces.

So the standard written form is:

• 解約金は高い。

Spaces are often added in textbooks or beginner materials to make the structure easier to see. They are not normally used in everyday Japanese writing.

In Japanese, 解約金 functions as one noun.

It is made from parts:

• 解約 = cancellation / contract termination
• 金 = money / fee

But together they form one compound noun:

• 解約金 = cancellation fee / termination charge

So in the sentence, the structure is:

• 解約金 = topic noun
• は = topic marker
• 高い = predicate adjective

The basic structure is:

• noun + は + adjective

So:

• 解約金 = cancellation fee
• は = topic marker
• 高い = high / expensive

Japanese often puts the main descriptive word at the end, so the sentence builds toward the final idea.

A very literal breakdown would be:

• As for the cancellation fee, high.

That sounds strange in English, but it is perfectly normal in Japanese.

Yes. 高い often reflects the speaker’s judgment.

So 解約金は高い。 can mean:

• the fee is objectively large
• the speaker feels it is too expensive
• the speaker is complaining about it

If you want to sound more objective or formal, Japanese might use other expressions in some contexts, but 高い is very common and natural in everyday speech.