It can be very confusing to know when to use there, their, or they're. These words all sound the same, but they have very different meanings. Here are some helpful tips:
There is used to tell or show where something is, to refer to a place. For example, "There is a coffee shop down the street," or, "The grocery store is over there."
Their is a possessive adjective. Possessive adjectives are used to show ownership, or what belongs to whom. As an example, "The children are wearing their boots," or, "They drink their tea with sugar."
They're is a contraction of they + are. For example, "They're going to Paris this summer," or, "I don't know if they're coming with us."
There, Their & They're Grammar Quiz
There, Their & They're Lessons: