This is the 82nd most frequent Japanese word.
山陽
"山陽" (Sanyō) refers to the southern side of a mountain or the Sanyō region in Japan.
In this sentence, '山陽' refers to a geographical region in Japan situated on the southern side of the Sanyo Shinkansen line.
山陽地方は温暖な気候で知られています。
The Sanyo region is known for its mild climate.
Here, '山陽' is used to denote the name of the bullet train line connecting cities in the western Honshu region of Japan.
山陽新幹線で広島まで行きました。
I went to Hiroshima by the Sanyo Shinkansen.
In this example, '山陽' is part of a proper noun referring to a specific high school, showing its usage in a name.