そこ is one of the forms of the
それ family of words used to identify things close to the listener. In this case it demonstrates a place. Just like
それ represents ‘that’,
そこ represents ‘that place’, or simply ‘there’.
-
そこの犬（いぬ）は危（あぶ）ないです。
That dog is dangerous. (That dog there, near you)
-
お前（まえ）のそこが悪（わる）い。
That right there is one bad thing about you. (That personality trait there, within you)
In the same way that
それ can be used to point back to something that was mentioned previously,
そこ can be used to point back to a place that was mentioned previously.
そこ should not be confused with そっち, a similar word which is also sometimes translated as ‘there’. そっち focuses more on the direction that one is/is going, while
そこ focuses purely on ‘that place’.