This is the 4598th most frequent Chinese word.
河西
"河西" means "west of the river."
Here, '河西' is used as a destination where the action of visiting is directed.
我要去河西看望朋友。
I am going to Hexi to visit a friend.
'河西' in this context serves as the setting where the learning happened.
在河西学到了很多有用的知识。
I learned a lot of useful knowledge in Hexi.
In this sentence, '河西' refers to a geographic location described as part of the city.