Questions & Answers about zhè shì xǐyīfěn.
这 means this. It points to something near the speaker.
In 这是洗衣粉, 这 is the subject of the sentence, so the structure is:
这 + 是 + 洗衣粉
this + is + laundry detergent
So the whole sentence literally follows the same basic pattern as English: This is laundry detergent.
是 means to be in the sense of is / am / are when connecting one noun to another noun.
In this sentence, it links:
- 这 = this
- 洗衣粉 = laundry detergent
So 这是洗衣粉 means This is laundry detergent.
A useful thing to remember: 是 is commonly used when one thing is being identified as another thing.