kensa ha asita hazimarimasu.

It is read:

けんさ は あした はじまります。
Kensa wa ashita hajimarimasu.

A few pronunciation notes:

• 検査 = けんさ
• は is written ha, but here it is pronounced wa because it is the topic particle.
• 明日 is commonly read あした in everyday speech. In some contexts, you may also see あす.

This is one of the first big spelling-vs-pronunciation things learners notice in Japanese.

When は is used as a particle, it is pronounced wa.
When it is part of a normal word, it is usually pronounced ha.

So in this sentence:

• 検査は = As for the examination / The examination
• the は marks 検査 as the topic of the sentence

This is just a standard rule of modern Japanese grammar.

The particle は marks the topic.

So 検査は means something like:

• As for the examination, ...
• The examination, ...

In natural English, we usually would not translate it literally. It mainly tells you what the sentence is about.

So the structure is:

• 検査は = topic
• 明日 = tomorrow
• 始まります = begins / will begin

Because time words often do not need a particle in Japanese.

Words like these commonly appear without a particle:

• 今日 = today
• 明日 = tomorrow
• 昨日 = yesterday
• 毎日 = every day

So 明日始まります is completely normal.

You can sometimes see particles with time expressions in other situations, but with a word like 明日, leaving it without a particle is very common and natural.

Japanese non-past forms often cover both:

• present
• future

So 始まります can mean:

• starts
• will start
• is going to start

The time word 明日 makes it clear that this sentence refers to the future.

This is very normal in Japanese. Japanese does not always mark the future with a special verb form the way English often does with will.

Because 始まる and 始める are different verbs.

• 始まる = to begin, to start (intransitive)
  
  • something begins on its own
• 始める = to begin something, to start something (transitive)
  
  • someone starts something

In this sentence, the examination is the thing that begins, so Japanese uses 始まります from 始まる.

Compare:

• 検査は明日始まります。
  The examination begins tomorrow.
• 医者が検査を明日始めます。
  The doctor will start the examination tomorrow.

The sentence follows a very common Japanese pattern:

[Topic] + [Time] + [Verb]

So here:

• 検査は = topic
• 明日 = time
• 始まります = verb

Japanese verbs usually come at the end of the sentence.

That is why the sentence feels different from English.
English might say:

• The examination will begin tomorrow.

Japanese often prefers:

• As for the examination, tomorrow begins.

That is not a natural English translation, but it helps show the structure.

For a beginner, it is often easiest to think of 検査 as the main thing being talked about, but technically は marks the topic, not necessarily the grammatical subject.

In many simple sentences, the topic and subject overlap closely enough that learners do not need to worry too much at first.

So for practical purposes, you can understand:

• 検査は = the examination as the thing this sentence is about

But grammar-wise, は is doing topic-marking, not the same job as が.

Yes, 検査が明日始まります is possible, but the nuance changes.

Very roughly:

• 検査は明日始まります。
  As for the examination, it starts tomorrow.
  This sounds like you are presenting information about the examination as a topic.

• 検査が明日始まります。
  This can sound more like identifying or emphasizing the examination as the thing that starts tomorrow.

For many beginners, the important point is:

• は = topic, often more general or contrastive
• が = subject marker, often more specific or focused

In a simple neutral statement like this, は is very natural.

始まります is the polite form.

The plain form is:

• 始まる

So:

• 検査は明日始まる。 = plain / casual
• 検査は明日始まります。 = polite

You would normally use 始まります in situations like:

• speaking to a customer
• speaking to a patient
• making an announcement
• talking politely in general

Since 検査 sounds like a medical or formal context, the polite form fits very well.

Not always.

明日 has a few common readings, especially:

• あした — very common in everyday conversation
• あす — also common, often a little more formal or announcement-like
• みょうにち — more formal or literary, and less common in everyday speech

In a sentence like this, あした is a very natural reading unless the context is especially formal.

Yes, Japanese word order is more flexible than English, as long as the particles make the roles clear and the verb stays near the end.

For example, these are possible:

• 検査は明日始まります。
• 明日、検査は始まります。

Both can work.

However, 検査は明日始まります is a very straightforward, natural order.

Even though Japanese allows some flexibility, not every order sounds equally natural in every situation. The original sentence is a very standard way to say it.

It sounds like a neutral, polite statement of schedule or timing.

Depending on context, it could be something like:

• a hospital staff member giving information
• an announcement
• a formal explanation of when something begins

It does not sound emotional or strongly emphatic.
It simply gives information in a polite, matter-of-fact way.