Bottom line:
1) There is no official language of the United States (though English is basically it)
2) Some kids that play high school soccer are not totally fluent in English..
3) Some kids that play high school soccer are not totally fluent in Spanish
4) If you understand both..you have the advantage.
Learn spanish if you don't want it to be a problem. Or.. beat the guy regardless.
If you're a ref..I think you can tell when a player is "dissenting" or being "unsporting"..without knowing what "Punta" actually means..