It literally translates to "the wide street", but it can also be used more metaphorically to refer to:
* A place where there is a lot of space or freedom: "He felt he needed to escape to la calle ancha, to find some peace and quiet."
* A place where there is a lot of activity or excitement: "The festival was a lively event, a real la calle ancha of music and dancing."
The specific meaning will depend on the context in which it is used.