word usage - When should I use "there" and "their"? - English Language Learners Stack Exchange
the differences of when to use there and their is so confusing
Why do so many people not know when to use there, their, or they’re?
Do you use "there is" or "there are" if you have more than 1 item but they're each in the singular, eg "there is/are a cat and a dog"? Does it change if the second item is in the plural?
When should you use there, their, and they’re?
Example of there, their, and they’re
How do you remember there, their, and they're?
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In grammatical terms, their is a possessive determiner, just like my, your, his, her, its and our. It indicates that what is described in the following noun phrase belongs to, or is in some other way associated with, the person or thing to which the possessive determiner refers. Just as my car is a car that belongs to me, so their house is a house that belongs to them.
There is a word with many uses. In your example, There are lots of skyscrapers in Dubai, it is what is sometimes called a ‘dummy subject’. It would be grammatical to say Lots of skyscrapers are in Dubai, but, generally, we don’t. We use there are (or there is) where French uses il est or il y a, German uses es ist, es sind or es gibt and Spanish uses hay.
Their means belonging to them, while there is a place or a "dummy subject." In your examples, you would say:
Their house is beautiful.
There are lots of skyscrapers in Dubai.
In the second example, there is a "dummy subject." In the following example, it is a place:
They are in the skyscraper over there.