Pronounced as jens, the word has several meanings.
1) One popular meaning is ‘sex.’
Example: جنسي کيسې (sex stories)
2) It is also used for gender.
Example: د ښځې او نر جنس (male female gender)
3) The third meaning is ‘edible.’ Its plural is: ajnaas.
Example: د غنمو جنس (edible wheat)
4) ‘Alike’ is another meaning.
Example: هر همجنس د خپل همجنس سره جوړېږي (رحمان بابا) (Everyone likes to be with their alike)
The word is originally from Arabic. An entry for this on Wikitionary can be found here.