A "white collar worker" is someone who works in an office (customer service, management, sales, etc.).
Example: There are mostly manufacturing positions here. There aren't many white-collar jobs.
The opposite of a white collar worker is a "blue collar worker."
A blue collar worker is someone who works with his hands (manufacturing, construction, maintenance, etc.).
"White collar" (and "blue collar") can also be used to describe a job, position, or place.
Text Source: 100 Useful Business English Expressions