The 2017 Confederations Cup is being hosted by 2018 FIFA World Cup hosts Russia and will run during June of 2017, the year before the World Cup is in Russia. The tournament combines the winners of each confederation around the world and as yet those teams are not decided. For the last cup nations competing included 2014 World Cup hosts Brazil, AFC Champions Japan, CONCACAF champions Mexico, CONMEBOL champions Uruguay, UEFA EURO 2012 Runners Up Italy, the CAF champions Nigeria and OFC champions Tahiti.
Brazil are the defending champions, they won the 2013 final beating Spain 3-0 and also won in 2009, beating USA 3-2, when the tournament was hosted in South Africa. You can find more information on the Confederations Cup here: Wikipedia or at the FIFA.com page.