kyou ha taityou ga warui node, kaisya wo yasumimasu.

今日 is being used as the topic here, so は is natural.

• 今日は = as for today / today
• It sets the scene for the rest of the sentence.

You often do not need に with words like:

• 今日
• 明日
• 昨日
• 毎日

These time words can usually appear without any particle when they mean when something happens.

So:

• 今日は体調が悪いので、会社を休みます。 = As for today, since I’m not feeling well, I’ll be absent from work.

If you used 今日に, that would sound unnatural in this sentence.

が marks what is in the state being described by 悪い.

Here, 体調が悪い literally means:

• my physical condition is bad
• more naturally: I’m not feeling well

So 体調 is the thing that is bad, which is why が is used.

This is very common with adjectives:

• 気分が悪い = I feel sick / unwell
• 頭が痛い = my head hurts
• 都合が悪い = it’s inconvenient / I’m not available

In Japanese, the thing experiencing the condition is often marked with が.

体調 means physical condition or health condition.

It is commonly used when talking about how your body feels, especially in everyday situations:

• 体調がいい = to feel well
• 体調が悪い = to feel unwell
• 体調を崩す = to fall ill / to have your health worsen

Compared with 病気:

• 体調が悪い is broader and softer
• 病気 means illness/disease, which sounds more specific

So 体調が悪い is very natural when someone says they are not feeling well enough to go to work.

Because ので attaches to the plain form of the word before it.

For an い-adjective like 悪い, the plain form is just:

• 悪い

So:

• 悪いので = because it is bad / because I’m not feeling well

You do not change 悪い to 悪く before ので.

Compare:

• 高いので = because it is expensive
• 寒いので = because it is cold
• 体調が悪いので = because I’m not feeling well

The -く form is used in other grammar patterns, but not here.

Both ので and から can mean because, but the nuance is different.

ので

• softer
• more explanatory
• often sounds more polite or less forceful
• common when giving a reason, especially in formal or considerate situations

から

• more direct
• more assertive
• often sounds more like the speaker’s own reasoning or insistence

In this sentence, ので fits well because saying you are taking time off work can sound more polite and less blunt:

• 体調が悪いので、会社を休みます。 = Since I’m not feeling well, I’ll be absent from work.

If you said:

• 体調が悪いから、会社を休みます。

it is still grammatical, but a little more direct.

This is very normal in Japanese.

In a sentence like this, the clause before ので often uses the plain form, even when the main sentence ends in polite style.

So:

• 体調が悪いので、会社を休みます。

is completely natural.

Japanese often mixes:

• plain form in subordinate clauses
• polite form in the main sentence

You could also hear more polite variations, such as:

• 体調が悪いので、会社を休ませていただきます。

But the original sentence is already natural and polite enough for many situations.

This is a very common point for learners.

Although 休む often means to rest or to take a break, it can also mean to be absent from a place such as:

• 学校を休む = to miss school
• 会社を休む = to miss work / be absent from the company
• 授業を休む = to miss class

Here, を marks the place or activity that is being missed.

So:

• 会社を休みます does not mean I rest the company
• it means I will be absent from work

This usage is standard Japanese.

Because 休む does not work that way here.

With 会社を休む, the company is the thing you are absent from, and Japanese uses を for that expression.

• 会社を休む = to take the day off from work
• 学校を休む = to be absent from school

Using に would not be correct in this pattern.

So you should learn X を休む as a set expression meaning:

• to miss X
• to be absent from X
• to take time off from X

No. It means the speaker is taking time off from work.

• 会社を休みます = I will be absent from work

If you want to say the company is closed, you would use a different expression, such as:

• 会社は休みです。 = The company is closed / off today.
• 会社が休みです。 = The company is off / not operating.

So in your sentence, the meaning is personal: I am not going to work today.

Yes, but it is usually omitted because it is understood from context.

The sentence could be:

• 私は今日は体調が悪いので、会社を休みます。

But Japanese often leaves out obvious subjects, especially I, when the context is clear.

That is why the more natural version is simply:

• 今日は体調が悪いので、会社を休みます。

This is one of the biggest differences from English: Japanese does not need to say I as often.

It is not strictly necessary, but it adds an important nuance.

With 今日:

• 今日は体調が悪いので、会社を休みます。
• Today, I’m not feeling well, so I’ll take the day off.

Without 今日:

• 体調が悪いので、会社を休みます。
• I’m not feeling well, so I’ll take the day off.

The version without 今日 is still natural, but the original makes the timing more explicit and can imply that this is today’s situation, not necessarily a general condition.

Yes, it is very common and feels quite natural.

Japanese speakers often use:

• 体調がいい = to feel well
• 体調が悪い = to feel unwell

It is one of the standard ways to talk about your physical condition.

Other similar expressions include:

• 気分が悪い = I feel sick / nauseous
• 具合が悪い = I feel unwell
• 調子が悪い = I’m not in good condition / something is wrong

Among these, 体調が悪い is especially common in workplaces, schools, and polite explanations.

It is polite-neutral and very natural.

Why?

• ので sounds softer and more considerate than から
• 休みます is the polite -ます form

So the sentence is suitable in many everyday situations, such as:

• telling a coworker
• informing your boss in a simple way
• messaging the office

However, if you need to sound more formal or humble, especially to a superior, you might say something like:

• 本日、体調が優れないので、会社を休ませていただきます。

That sounds more formal than the original.

Still, the original sentence is perfectly good everyday Japanese.

It is read:

• たいちょう

So the full sentence is read:

• きょう は たいちょう が わるい ので、かいしゃ を やすみます。

Word by word:

• 今日（きょう） = today
• 体調（たいちょう） = physical condition
• 悪い（わるい） = bad
• 会社（かいしゃ） = company
• 休みます（やすみます） = take a day off / be absent

Yes, that is a natural English translation, but it is a little stronger than the Japanese.

Japanese 体調が悪い does not always mean the speaker is definitely sick with an illness. It can also mean:

• not feeling well
• under the weather
• physically off
• not in good condition

So depending on context, good English translations include:

• I’m not feeling well today, so I’m taking the day off work.
• Since I’m feeling unwell today, I’ll be absent from work.
• I’m under the weather today, so I’m taking off work.

So I’m sick is possible, but sometimes slightly more definite than the Japanese.