Answers: "Their" refers to something owned by "them". For example, "They won't lend me their car" is the use of "their".
"They're", which is an abbreviation of "They are", can refer to something that "they" are doing, or an aspect/quality of "them". For example, "They're going to the park tomorrow" and "I just think that they're really rude" are both uses of "they're".
"There" refers to a place or position of something. For example, "The TV remote is over there" is a use of "there".
Hope this helps!
