This composite character is the noun goods with the addition of three counting rods (the numeral three). The numeral indicates the relative size of the shipment. Hence, Mahadevan's sign number
1016 is an ideograph for a large quantity of goods.
Illustrative Text Reference:
Mohenjo-daro: Seal: M-638 a: Sayid Ghulam Mustafa Shah and Asko Parpola, 1991: Corpus of Indus Seals and Inscriptions: Volume 2: Page 21: Collections in Pakistan: Suomalainen Tiedeakatemia.
Indus Script Sign Number 1016: List of Sign Variants: Iravatham Mahadevan, 1977: The Indus Script: Texts, Concordance and Tables: The Director General Archaeological Survey of India.