Currently FIFA schedules out international breaks and tournaments in a haphazard schedule based primarily on what is best for Europe’s top leagues. The primary tournament break is in the summer with international breaks for things like World Cup Qualifying taking up a long weekend every other month (essentially).
In 2018, there is a FIFA break in March (19-27). From June 14 to July 15 there is the World Cup in Russia and December 12 to December 22 is the Club World Cup. This only addresses events at the senior men’s level. Women’s and youth soccer operate on different calendars.