This is the 499th most frequent Chinese word.
求
"To seek; to request; to strive for."
In this sentence, '求' is used as a verb meaning 'to request' or 'to ask for' assistance or help.
他向老师求帮助。
He asked the teacher for help.
Here, '求' is part of '祈求', which conveys the act of solemnly asking or begging, often with emotional or spiritual connotation.
他们在祈求好运。
They are beseeching for good fortune.
In this context, '求' signifies the necessity or requirement for rain, related to 'seeking or desiring' a beneficial condition or outcome.