One must به جای must

Question

یه جمله دیدم به جای must جمله به این شکل بود

One must be meticulous 

باید دقیق بود

نقش one اینجا چیه

Answer 1

آدم.

any person or thing;
people in general:

One shouldn't cry over spilled milk (= People in general, including the speaker, shouldn't get upset about things that can't be fixed.)