What is the use of + and - in a search query

What is the use of '+' operator in a search string?

A search operator (sometimes referred to as a search parameter) is a character or string of characters used in a search engine query to narrow the focus of the search. In mathematics and computer science, operators are characters or sequences of characters that represent an action or cause an action to be performed.

And I have no clue what "-" does.

Brainleist is appreciated

The use of + and - in a search query is -