help please

Dear all

I just got a letter from NSC telling me(EB2 from mainland) to do code 1 biometrics for my I485 after I140 apprival about 8 months, can any friends here tell

1.what does that mean to do that?
2.do most of you guys need to do that?
3.what could happen after doing that,
4.how long it will take? etc.

thank you so much for your kind of input.

Merry Christmas

Darktiger