Complex sentence: Belgium qualified for only one out of eight major tournaments in the 1950s and 1960s: the 1954 World Cup, on the eve of which the Belgian, French and Italian football boards founded UEFA.
Split into simpler sentences: Belgium qualified for only one of eight major tournaments in the 1950s and 1960s; the 1954 World Cup. The day before the tournament began, the Belgian, French and Italian football boards founded UEFA.