Earlier quoted context omitted.
FISA has provisions for surveilling "facilities", buildings, and locations, and is not limited to orders to surveil just an individual. A more generous reading would suggest that is what "foreign entity" is referring to - cases where the NSA is surveilling a safehouse or a military base and not necessarily a human being.
A foreign company might also qualify as an entity. Even a company that merely has offices abroad might qualify. US Citizens who work for foreign entities might very well be included.
Even foreign persons who are under surveillance are to be excluded when they travel to the US.