Where does “पुल्लिंग” come from?

पुल्लिंग (Hindi) comes from Sanskrit पुल्लिङ्ग, from Sanskrit पुंस्, from Proto-Indo-European péwmōs ~ pumsés.

पुल्लिंग (Hindi): masculine gender

Definitions

Step	Language	Word	Meaning
1	Sanskrit	पुल्लिङ्ग	—
2	Sanskrit	पुंस्	a man, male being; a masculine word; a human...
3	Proto-Indo-European	péwmōs ~ pumsés	—

पुल्लिंग — Etymology, Origin & Word History | Etymology Explorer