Fruits are full of phytochemicals like polyphenols that have shown interesting health effects. Coffee has quite a high polyphenols content too.
Some fruits have some compounds, along thousands of unspecified others, which seem to have a beneficial effect, most often in-vitro.
Regarding polyphenols, there is no hard, concrete evidence that any have actual positive health benefits.
One thing is for sure, the marketing surrounding these "5 a day to be healthy" is extremely strong and widespread.