The Indus Dictionary Project
This is a pictograph of two mountain ranges with a space between them. It is the noun mountain pass.
Mohenjo-daro: Seal: M-326 a: Jagat Pati Joshi and Asko Parpola, 1987: Corpus of Indus Seals and Inscriptions: Volume 1: Page 82: Collections in India: Suomalainen Tiedeakatemia.
There is only one extant example of this Indus sign.
Indus Script Sign Number 231: Sign List of the Indus Script: Iravatham Mahadevan, 1977: The Indus Script: Texts, Concordance and Tables: The Director General Archaeological Survey of India.