What is this mean?

Depends on where you found this sentence, I reckon.

Of course.

The explanation of the idiom: bat a thousend

Some wishes to musicians I guess, like "Have a nice day"

The hole example:

"bat a thousand - have a perfect record. He is so happy that
everyone he invited to the party is coming. He’s batting a thousand."

Could it mean "absolute success"?

Yes, you are right. For example, I've had two interviews and two offers. I'm batting a thousand!

Ok, thank you odexed!

@CK, @AlanF_US, ( @Cangarejo ) when do you use the expression "perfect record"?

It refers to a set that contains no failures, only successes. "Batting a thousand" means that every time a person has had a baseball pitched (thrown) to them, they've hit it successfully. A batting average is usually given as a figure between 0 and 1, and to make the figure easier to say, it's multiplied by 1000. Thus, a perfect batting average is a thousand.

Does it only refer to baseball?

No.

Thank you very much.