yàoshi nǐ xiànzài bù xiūxi, wǎnshang huì hěn lèi.

要是 means if in this sentence.

It works very much like 如果, but 要是 is usually a little more conversational and common in everyday speech. So:

• 要是你现在不休息，晚上会很累。
• 如果你现在不休息，晚上会很累。

Both mean the same thing here.

A rough feel is:

• 如果 = if
• 要是 = if / if it happens that / if you were to

In normal conversation, 要是 sounds very natural.

In Mandarin, you often do not need to say then explicitly.

The sentence is:

• 要是你现在不休息，晚上会很累。

Literally, that is something like:

• If you now don’t rest, evening will be very tired.

English usually likes if..., then..., but Chinese often just uses:

• 要是 / 如果 + condition, result

You can add 那 in the second clause for emphasis:

• 要是你现在不休息，那你晚上会很累。

That means:

• If you don’t rest now, then you’ll be very tired tonight.

But 那 is optional here.

Chinese usually puts time words before the verb phrase.

So:

• 你现在不休息
• literally: you now not rest

This is the normal order:

• subject + time + verb phrase

Examples:

• 我今天上班。 = I work today.
• 他明天来。 = He is coming tomorrow.
• 你现在不休息。 = You are not resting now / If you don’t rest now

So 现在 comes before 不休息 because it tells you when the action happens.

不 is used to negate habitual actions, present/future actions, intentions, or general statements.

Here, the meaning is about a present or future choice:

• 你现在不休息
• if you don’t rest now

So 不 is correct.

没 is usually used for:

• things that didn’t happen
• completed actions in the past
• have not done something

Compare:

• 你现在不休息。 = You are not resting now / If you don’t rest now
• 你昨天没休息。 = You didn’t rest yesterday

So this sentence needs 不, not 没.

Here, 休息 is a verb, meaning to rest.

So:

• 不休息 = not rest

Chinese words are often flexible, and 休息 can sometimes relate to the idea of rest more generally, but in this sentence it clearly functions as a verb.

Examples:

• 我想休息。 = I want to rest.
• 你该休息了。 = You should rest.
• 他在休息。 = He is resting.

Chinese often does not use prepositions the same way English does for time expressions.

In English, you say:

• at night
• in the evening
• tonight

In Chinese, a time word like 晚上 can simply appear in the sentence by itself:

• 晚上会很累
• literally: evening will very tired

This naturally means:

• you’ll be very tired tonight / in the evening

So 晚上 is functioning as a time expression, and no extra word like in or at is necessary.

Here, 会 shows likelihood, prediction, or what will happen.

So:

• 晚上会很累 means
• you will be very tired tonight

In this sentence, 会 does not mean can in the sense of ability. It means something more like:

• will
• is likely to
• would

Because the sentence is making a prediction based on a condition:

• If you don’t rest now, you’ll be very tired tonight.

This is a very common question.

In Chinese, when an adjective like 累 is used as the predicate, it often needs 很 or another degree word in front of it.

So:

• 很累 literally looks like very tired
• but in many cases it simply means tired

That means 很 is often not strongly emphatic here. It can just make the sentence sound natural.

Compare:

• 我累。 — grammatical in some contexts, but often sounds abrupt or contrastive
• 我很累。 — normal, natural way to say I’m tired

In this sentence, 会很累 can be translated as:

• will be tired or
• will be very tired

Depending on context, both are possible. Since the sentence is a warning, very tired is a natural translation.

累 is usually treated as an adjective meaning tired.

So:

• 很累 = tired / very tired

Chinese adjectives often behave a bit like verbs in sentences, which is why learners sometimes get confused. For example:

• 我很累。 = I am tired.
• literally: I very tired.

There is no separate word like am in the Chinese sentence. That is normal.

So while 累 means an adjective-like idea, it can appear directly as the main predicate.

That sounds unnatural.

The natural word order is:

• 晚上会很累

Time expressions usually come before the verb or adjective phrase they modify.

So the sentence is:

• 你现在不休息，晚上会很累。

Not:

• 你会晚上很累

A better way to think of the structure is:

• 晚上 = time
• 会 = will / likely to
• 很累 = be tired

So the order is:

• time + 会 + adjective

It is not required, because the subject is already clear from context.

The sentence says:

• 要是你现在不休息，晚上会很累。

This is understood as:

• If you don’t rest now, you’ll be very tired tonight.

Chinese often omits repeated subjects when they are obvious.

But you can include it:

• 要是你现在不休息，你晚上会很累。
• 要是你现在不休息，那你晚上会很累。

These are also correct. The version without the second 你 is just smoother and more economical.

Because of 现在, it specifically refers to now / at this point.

So the sense is:

• If you don’t get some rest now...

Without 现在, the sentence would be more general:

• 要是你不休息，晚上会很累。
• If you don’t rest, you’ll be very tired tonight.

Adding 现在 makes the warning more immediate.

Yes, that is possible, but If you don’t rest now, you’ll be tired tonight is usually the more natural translation.

Chinese does not always force the same tense distinction English does. So:

• 你现在不休息

could be understood from context as:

• you are not resting now or
• you don’t rest now

But in this conditional sentence, the intended meaning is usually a warning about what someone should do now, so English normally prefers:

• If you don’t rest now, you’ll be very tired tonight.

That captures the meaning best.