job offer裡的option？ - offer

最近收到了一家小公司的offer, salary挺不錯的
但是offer letter裡關於股票的部份我實在看不太懂…

信裡寫
the Company grant you an option to purchase 400 shares of the
Company’s Common Stock at a price per share equal to the fair
market value per share of the Common Stock on the date of grant,
as determined by the Company’s Board of Directors. 25% of the
shares subject to the option shall vest 12 months after the date
your vesting begins subject to your continuing employment
with the Company. The remaining shares shall vest monthly over
the next 36 months in equal monthly amounts subject to your
continuing employment with the Company.

是說我可以用市價買他公司的股票，
但是會被鎖，要工作三年才會全拿到？
這樣對我應該沒特別的好處啊？
請問是否我解讀錯誤了？

謝謝！

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Sent from JPTT on my LGE LGLS740.

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