Question

My brother works in a bank meets people of different ages. Their is a mistake in this sententce, What is it?

Answer 1

The mistake must be about writing the whole sentence without an 'and' when it was needed.

Explanation:

The answer should be My brother works in a bank, and he meets people of different ages. If you do not put the and the sentence doesn't make sense because there are two verbs.

Answer 2

My brother , who works in a bank , meets people of different ages.

Explanation:

Apart from the answer already posted, it could also be:
My brother , who works in a bank , meets people of different ages.