Complex sentence: The NHL uses a 2-2-1-1-1 format; that is to say, one team hosts the first two games at its home stadium, and the next two shift to the opposing team's stadium.
Split into simpler sentences: The NHL uses a 2-2-1-1-1 format. In other words, one team hosts the first two games at its home stadium, and the next two shift to the opposing team's stadium.