What does correlation does not mean causation mean?

Answer 1

People with bigger feet have higher intelligence, and people with smaller feet have lower intelligence. In other words, foot size is correlated with intelligence.

However, it's clear that if I could have made my feet bigger it would not have made me more intelligent. In other words, in increase in foot size is not a cause of greater intelligence.

That's what 'correlation does not imply causation' means.