Answer:
It means sounding logical in a statement.
Explanation:
In the sentence provided, "Racers, start your engines" the word <em>Racers</em> represents a noun of direct address.
These nouns of direct address are defined as words that name a person, places, things or ideas. In the particular case of the sentence provided this name (Racers) reffers to the persons who are taking part in the career.
