Hang on. What does it mean to disable this? 1. Does it disable measurement? - or - 2. Does it disable the privacy-preserving feature, i.e., enable tracking?

Hang on. What does it mean to disable this? 1. Does it disable measurement? - or - 2. Does it disable the privacy-preserving feature, i.e., enable tracking? What I really want to know: is it better for me to check the box or not?