Asking H-1B_tax and stp

In your previous post, "關於一方在中國TAX", item 5 - "5. The spouse can exclude foreign earned income up to $80,000. This would take out anything you put in line 7 in above 2, since most people in China do not make $80,000."

Could you explain it in details how to take the exclusion from foreign earned income? Are there any specific forms for this purpose?

Thanks.