There, from Dictionary.com:
[th air; unstressed th er]
–adverb
1. in or at that place (opposed to here): She is there now.
2. at that point in an action, speech, etc.: He stopped there for applause.
3. in that matter, particular, or respect: His anger was justified there.
4. into or to that place; thither: We went there last year.
5. (used by way of calling attention to something or someone): There they go.
6. in or at that place where you are: Well, hi there.
–pronoun
7. (used to introduce a sentence or clause in which the verb comes before its subject or has no complement): There is no hope.
8. that place: He comes from there, too.
9. that point.
–noun
10. that state or condition: I'll introduce you to her, but you're on your own from there on.
–adjective
11. (used for emphasis, especially after a noun modified by a demonstrative adjective): Ask that man there.
–interjection
12. (used to express satisfaction, relief, encouragement, approval, consolation, etc.): There! It's done.
Their, from Dictionary.com:
[th air; unstressed th er]
–pronoun
1. a form of the possessive case of they used as an attributive adjective, before a noun: their home; their rights as citizens; their departure for Rome.
2. (used after an indefinite singular antecedent in place of the definite masculine form his or the definite feminine form her): Someone left their book on the table. Did everyone bring their lunch?
They're, from Dictionary.com:
[th air; unstressed th er]
contraction of they are.
All used in one sentence: They're moving their bed over there.