zhè shì xǐyīyè.

这 can stand alone as a pronoun meaning this.

In 这是洗衣液。, 这 means this and is the subject of the sentence:

• 这 = this
• 是 = is
• 洗衣液 = laundry detergent

You use 这个 when 这 is directly modifying a noun, usually with a measure word:

• 这个东西 = this thing
• 这瓶洗衣液 = this bottle of laundry detergent

So:

• 这是洗衣液。 = This is laundry detergent.
• 这瓶是洗衣液。 = This bottle contains laundry detergent / This bottle is laundry detergent

是 is often translated as to be, but it does not work exactly like English to be.

In this sentence, 是 links one noun-like thing to another for identification:

• 这 = this
• 是 = is
• 洗衣液 = laundry detergent

So the structure is:

A 是 B
= A is B

This is very common when saying what something is:

• 这是水。 = This is water.
• 那是老师。 = That is a teacher.

But unlike English, Mandarin often does not use 是 before adjectives:

• 它很大。 = It is big.
  Not: 它是大。

So in this sentence, 是 is correct because 洗衣液 is a noun.

Mandarin does not have articles like a, an, or the.

So 这是洗衣液。 could mean:

• This is laundry detergent
• This is the laundry detergent

The exact meaning depends on context.

This is very normal in Chinese. Many times, context does the work that articles do in English.

No, not here.

When 这 means this one / this thing, it can stand alone:

• 这是什么？ = What is this?
• 这是洗衣液。 = This is laundry detergent.

But if 这 comes directly before a noun, you usually need a measure word:

• 这瓶洗衣液 = this bottle of laundry detergent
• 这袋洗衣液 = this bag of laundry detergent

So:

• 这 是 洗衣液。 = correct
• 这洗衣液 = usually not correct as a full phrase

洗衣液 is a compound word:

• 洗 = wash
• 衣 = clothes
• 液 = liquid

So literally it means something like clothes-washing liquid, which is why it means laundry detergent or liquid laundry detergent.

This is a useful pattern in Chinese: many words are built from smaller meaningful parts.

In this sentence, 这 is pronounced zhè with a 4th tone.

By itself:

• 这 = zhè

Before a measure word, in natural speech, many speakers pronounce it more like zhèi:

• 这个 often sounds like zhège or zhèige depending on accent and speech style
• 这本书 may sound closer to zhè běn shū or zhèi běn shū in actual speech

But for 这是洗衣液。, just learn and say:

• zhè shì xǐyīyè

The pinyin is xǐ yī yè:

• 洗 = xǐ (3rd tone)
• 衣 = yī (1st tone)
• 液 = yè (4th tone)

A natural rhythm is:

• zhè shì xǐ-yī-yè

A few pronunciation tips:

• x in xǐ is a soft Mandarin sound, not like English ks
• yī is just yee
• yè sounds like yeh with a falling tone

There is no special tone change inside 洗衣液.

Yes, there are other words depending on region and product type.

Common possibilities include:

• 洗衣液 = liquid laundry detergent
• 洗衣粉 = laundry powder / powdered detergent

洗衣液 is specifically the liquid kind, so it is a good choice if that is what you mean.

If you are talking about the general substance in a bottle, 洗衣液 is very natural in modern Mandarin.

Usually no, not if you want to say This is laundry detergent.

这洗衣液 sounds incomplete or means something more like this laundry detergent..., as if more words are coming:

• 这洗衣液很好用。 = This laundry detergent is very useful/effective.

To identify something, you normally say:

• 这是洗衣液。

So 是 is needed here.

The easiest way is to add 吗 at the end:

• 这是洗衣液吗？ = Is this laundry detergent?

Another common question is:

• 这是什么？ = What is this?

And the answer would be:

• 这是洗衣液。

This is a very useful basic pattern:

• 这是什么？
• 这是……。

Yes.

In 这是洗衣液。:

• 这 = subject (this)
• 是 = linking verb
• 洗衣液 = predicate noun / what the thing is identified as

So the structure is basically:

Subject + 是 + Noun

This is one of the most basic sentence patterns in Mandarin.

Yes.

Because Mandarin does not mark a/the, the sentence can be understood in different ways depending on context.

For example:

• If you are pointing at a bottle and explaining what it is, 这是洗衣液。 = This is laundry detergent.
• If someone asks which product is the detergent, 这是洗衣液。 could mean This is the detergent.

Context tells the listener which interpretation is correct.

The sentence ends with the Chinese full stop:

• 。

So the full sentence is:

• 这是洗衣液。

In Chinese writing, this small circle is the normal period-like punctuation mark.