This is the 6368th most frequent Korean word.
안산
"Ansan" is a city in South Korea.
In this sentence, '안산' is used as a proper noun to refer to a specific city in South Korea.
안산은 경기도에 있는 도시입니다.
Ansan is a city in Gyeonggi Province.
Here, '안산' is again a proper noun referring to the city, placed as the object of the action 'visit'.
우리 가족은 주말마다 안산을 방문합니다.
My family visits Ansan every weekend.
In this usage, '안산' is highlighted to identify the city known for its industry.