The third-person possessive adjective
Encoding Strategies:
repetition

Su means his, her , its, or their and is the third-person possessive. Spanish uses the same word whether the owner is he, she, it, or they.
su
his, her, its, their
The possessive adjective for any third-person owner.
Los niños hicieron su tareaThe children did their homework
Dejó su abrigo en la sillaHe left his coat on the chair
your (formal address)
'Usted' evolved from the old Spanish phrase for "your grace" (a third-person phrase), so it kept third-person grammar.
¿Usted tiene su pasaporte?Do you have your passport?
Señor García, su mesa está listaMr. García, your table is ready