Hello Hemlata!

Two categories for reservation are followed more or less same everywhere:
1. Vertical (category)- SC/ST/OBC of UP
2. Horizontal (sub category)- FF/AF/HC or PWD/GL of UP
GN stands for GENERAL.
You belong to general (your) so no vertical reservation available for you.
Being a girl you are eligible for horizontally reserved seats means you will get the benefit of 20% seats (minimum) reserved for girls in every branch & overall in institute.

OS: the other state- all the other students who are not from home state quota.

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Hope your doubts are solved.