Many languages have separate singular and plural forms for the second person (ways of saying “you”), but standard English does not. “You” can be addressed to an individual or a whole room full of people.
In casual speech, Americans have evolved the slangy expression “you guys” to function as a second-person plural, formerly used of males only but now extended to both sexes, but this is not appropriate in formal contexts. Diners in fine restaurants are often irritated by clueless waiters who ask “Can I get you guys anything?”
The problem is much more serious when extended to the possessive: “You guys’s dessert will be ready in a minute.” Some people even create a double possessive by saying “your guys’s dessert. . . .” This is extremely clumsy. When dealing with people you don’t know intimately, it’s best to stick with “you” and “your” no matter how many people you’re addressing.