It’s the literal english translation of mo’s name mo guan shan :)
If you type "don't close mountain" into Google translate it says
"Bùyào guānshān" basically means "I don't want guanshan"
That's my odd guess at what that could have said.
Probably mistranslations somewhere along the way.
Whoops
Mò 莫 also means do not in chinese. My bad for the first comment.
It basically just spells mo guanshan then if you use chinese characters.
莫关山
Yup! And here He Tian gave Mo that english nickname because he translated Mo’s name in english :) http://www.mangago.zone/read-manga/19_days/bt/manga/19_days/c173/pg-8/
This is so fucking stupid but sometimes I have a hard time understanding things... don’t close mountain.... what’s the funny part about it ..... I know I know I’m stupid lol just please tell me with out making fun of me