开一个生日会 explanation as to why 开 is used here? My book says that &quot;to host a party&quot; is written as...
开一个生日会
Example:
她想在家里开一个生日会。
The reason I am confused is because everywhere I look, 开 means to open. However, the book translates it as &quot;to hold&quot;. I have been told that the 你好 book, which is what I am learning from, can translate some words in strange ways so I guess what I am asking is, if this sentence is correct, why is 开 used?
开会 (“to host/attend a meeting”) is an example of a separable verb—we can add content between the two characters. The 开 relates to the “hosting” whereas the 会 relates to the “meeting”, and the in-between content modifies the 会.
For example, we might say:

他在开一个会。  (“He is hosting a meeting.”)
我们周五开一个三个小时的会。  (“On Fridays, we host a 3-hour meeting.”)

In the given example, instead of a 会(“meeting”), it’s a 生日会 (“birthday party”), but the same idea applies.

开一个生日会 (“to host a birthday party”)
爸爸开儿子的生日会。 (“The father hosted his son’s birthday party.)

Alternatively, we can think of 开 itself as an independent verb.