This is huuuuge. Sano was easily the top Latin American talent available this year. He received a 3.15 million signing bonus. The 16 year old shortstop probably will move to third base in the future as he is a big kid who still has some filling out to do.
With the signing of Sano, Max Kepler, who is widely believed to be the best player to ever come out of Europe, and 1st round pick Kyle Gibson, who was a top 5-10 talent, the Twins now have one of the best 5-10 farm systems in baseball.
Here is a good video on Sano, courtesy of MLBTR.