This is a pictograph of a bow with an arrow. Hence, it is the noun weapons, or the adjective armed.
Illustrative Text References:
Mohenjo-daro: Seal: M-28 a: Jagat Pati Joshi and Asko Parpola, 1987: Corpus of Indus Seals and Inscriptions: Volume 1: Page 16: Collections in India: Suomalainen Tiedeakatemia.
Gola Dhoro: New find: No CISI number: Hollow seal: Ancient Indus seal found at Gola Dhoro: Photograph [NB. the image has to be flipped in order to resemble a sealing]: © Kuldeep Bhan: https://www.harappa.com/goladhoro/goladhoroseal.html: Accessed: 19 February 2016.
Comment:
In the inscription on the hollow seal from Ghola Dhoro, this symbol is repeated. In that context, it might be translated as 'fortified'.
Image Credit:
Indus Script Sign Number 307: Sign List of the Indus Script: Iravatham Mahadevan, 1977: The Indus Script: Texts, Concordance and Tables: The Director General Archaeological Survey of India.