it is a polite counter for people,for example, "a honored/distinguished/important guest",we can translate into "一位贵宾" in chinese. "a friend",you can translate into "一个朋友"in informal situation,and you also can traslate into"一位朋友"in formal situation.it just depends on the situation you r in.

位 = polite counter for people It is the same as the informal counter 个。

In particular, 位 is a counter word.

Just mean “who..“ 哪位 =谁

thank you!