Here's the breakdown:
* Juan: A common Spanish masculine name, equivalent to "John" in English.
* es: "is" in Spanish, a verb that connects the subject (Juan) to the predicate (his name).
* su: "his" or "her," a possessive adjective indicating that the name belongs to someone else.
* nombre: "name" in Spanish.
Therefore, the sentence "Juan es su nombre" tells us that someone else's name is Juan.