Correlation coefficient is between -1 and 1, what is full negative or positive meaningful association between variables. Zero is equal of no association.
If I know any data and know correlation coefficient I can get invisible for me data. For example: Netflix collect users' rates for cinema - first variable.
Netflix know equal cinema and can get recommendation for people, because they are can continuous do typical rate without user (or use another peoples' rate who equal to based user) and understand his opinion about film what ha don't watch.
Correlations is communication between two various variables in the various measure, but it's possible!
Conclusions: I need to get more experience ...