Hii

The category rank for JEE would mean that in a particular category which you belong to like OBC, ST, SC etc where do you hold a place. The general ranks would mean your rank amongst all the students based on marks. But category rank gives your rank in one particular category only excluding all other category students.
Like in an exam if 1000 students had appeared in total and out of this 400 students are from obc category and you also belong to obc. Your general rank will be calculated by taking total no. of students as 1000 but category rank will be calculated by taking no. of students as 400 only.

Feel free to revert back incase of doubt.

Hope this helps
Thanks!