What do the Olympic rings actually mean?

The Olympic flag displays five interlocking rings and the colours blue, yellow, black, green and red on a white background and was chosen by Pierre de Coubertin because they appeared on all the national flags that competed in the Olympic games at that time. The interlocking rings meanwhile symbolise the universal Olympic spirit.
However, and up until 1951, the official Olympic handbook claimed that each colour represented a specific continent: red was for the Americas, blue for Europe, green for Australia and Oceania, yellow for Asia and black for Africa. Nonetheless, the Olympic Committee later announced this was not the case reiterating the notion that the rings represent the union of the five continents.
source: wikipedia