Its a grammar point, as iCake said, demonstrative pronoun: "a common use of тот to refer to a recently mentioned noun". Example from book I'm studying now:
Она проводила Анну Вениаминовну до дому, та пригласила зайти. So та is referring Анна Вениаминовна. (From story by Людмила Улицкая. Явление Природы.) examples everywhere.