This is the 7662nd most frequent Japanese word.
北湯口
"北湯口" is not a standard Japanese word or term; it appears to be a combination of characters meaning "north" (北), "hot water" (湯), and "entrance" (口).
In this sentence, '北湯口' is being used as a proper noun to indicate the name of a location, specifically a hot spring town.
北湯口は静かな温泉地です。
Kitayuguchi is a quiet hot spring town.
Here, '北湯口' refers to a geographic location where an event, the opening of a new inn, has occurred.
北湯口で新しい旅館が開業しました。
A new inn has opened in Kitayuguchi.
In this example, '北湯口' is again used as the name of a place, and the sentence describes an activity, exploration, in its vicinity.