This is the 54th most frequent Urdu word.
شروع
Begin; Start.
In this sentence, 'شروع' is used as a verb conveying the act of starting an activity, in this case, reading a book.
میں نے اپنی کتاب پڑھنا شروع کی۔
I started reading my book.
Here, 'شروع' functions as a noun, depicting the commencement of work as a subject of discussion.
کام شروع ہونے میں ابھی کچھ وقت ہے۔
There is still some time for work to start.
'شروع' is used as an adjective in this context, modifying 'دن' (day) to describe the 'first day'.