A more thorough explanation:

Definition: Emphasis added is a citation signal used to indicate that the writer quoting someone else's words has added emphasis to some of the words by italicizing or underlining them. It is also known as emphasis supplied.

Original quote: "I never said she stole my money."

Quote with emphasis added: "I never said she stole my money."

In this example, the writer has added emphasis to the word "never" to highlight the fact that they did not make the statement in question.

Original quote: "The book was not very interesting."

Quote with emphasis added: "The book was not very interesting."

In this example, the writer has added emphasis to the word "not" to emphasize their opinion that the book was not interesting.

Original quote: "The company will be profitable this year."

Quote with emphasis added: "The company will be profitable this year."

In this example, the writer has added emphasis to the phrase "this year" to highlight the specific time frame in which the company is expected to be profitable.