The Indus Dictionary Project
This is a pictograph of a barley seed. Hence, it is the noun barley grain.
Lothal: Seal impression: L-187 A: Jagat Pati Joshi and Asko Parpola, 1987: Corpus of Indus Seals and Inscriptions: Volume 1: Page 281: Collections in India: Suomalainen Tiedeakatemia.
There is only one extant example of this symbol in the Indus texts. It was found on a tag at Lothal, where the tag may have fallen off a grain sack.
Indus Script Sign Number 378: Sign List of the Indus Script: Iravatham Mahadevan, 1977: The Indus Script: Texts, Concordance and Tables: The Director General Archaeological Survey of India.