Complex sentence: There are 30 teams, with 23 in the U.S. and 7 in Canada, with the 31st team expanded to Las Vegas, Nevada starting for the 2017-2018 season.
Split into simpler sentences: There are 30 teams, with 23 in the U.S. and 7 in Canada. The NHL will officially expand to Las Vegas, Nevada for the 2017-2018 season.