This is a pictograph of a tally stick. The five horizontal notches on the stick mean that the unit count was precisely five.
Illustrative Text Reference:
Mohenjo-daro: Seal: M-920 a: Sayid Ghulam Mustafa Shah and Asko Parpola, 1991: Corpus of Indus Seals and Inscriptions: Volume 2: Page 88: Collections in Pakistan: Suomalainen Tiedeakatemia.
Image Credit:
Indus Script Sign Number 1219: List of Sign Variants: Iravatham Mahadevan, 1977: The Indus Script: Texts, Concordance and Tables: The Director General Archaeological Survey of India.