What does "go out there" mean as used by athletes in baseball, basketball, etc

If someone is performing (an athlete or team player or person talking to an audience), go out there is used to mean: go to the place where the event is occurring, a stage, a baseball field, and do [whatever], make baskets, hit a home run, hit under par (in golf).

When you go out onto a field, you can be seen by the public, as opposed to sitting on the bench, locker room or on the sidelines.

A basketball or baseball player would not use that idiom unless the public is seeing him or her. They would not use it in a closed practice session.

PLEASE NOTE: It is quite amusing that a basketball player chooses to use a baseball term. It shows the extent to which certain idioms permeate the language, even a pro ball player like this.

To hit a home run = score four points by running around the three bases and back to home plate. It is the highest number of points one person can get when playing baseball.

A typical comment might be: Go out there and knock 'em dead, kid.

go out, to be seen by the public, in this particular case.