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’.
That dog is dangerous. (That dog there, near you)
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.
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’.