What does "one" here refer to :Flirting is a woman's trade, one must keep in practice. -BecomingJane
"Flirting is a woman's trade, one must keep in practice."

This sentence is from the movie .

I have two questions:

1. How to use the phase "sth is a sb's trade"?
In what situation, whether it's polit/formal/frendly?

2. "one must keep in practice". What does the word "one" here refer to?

Thanks!Can't type movie name here?
It's from the movie "Becoming Jane".

Question

What does "one" here refer to :Flirting is a woman's trade, one must keep in practice. -BecomingJane
"Flirting is a woman's trade, one must keep in practice."

This sentence is from the movie .

I have two questions:

1. How to use the phase "sth is a sb's trade"?
    In what situation, whether it's polit/formal/frendly?

2. "one must keep in practice". What does the word "one" here refer to?

Thanks!Can't type movie name here?
It's from the movie "Becoming Jane".

Answer

If I said 'Drinking beer is a man's trade, one must keep in practice' I would be jokingly referring to my beer drinking as a man's right or prerogative by calling it a 'job' and I would use 'one must keep in practice' to justify my doing it repeatedly.
The same thing applies here, she enjoys flirting.

Answer

You must work hard in order to make your dream come true. 你只有勤奋努力，才能梦想成真。<<>> One must work hard in order... true. 一个人只有勤奋努力，才能梦想成真。

Answer

Let's come to your second question here as it is easier: the word "one" here refers to "a woman", according to the context. (Flirting is a woman's trade, one must keep in practice.)
As to your first question, "someone's trade" (roughly) means something that he or she depends on for a living. So, according to this sentence, the speaker thinks that a woman depends on flirting for a living, so she must keep practicing it.
I hope this can help you understand.