This is a pictograph of an elephant's tail. It was used as a classifier (counter or measure word) for elephants. A modern translation might be the noun parade.
Illustrative Text Reference:
Mohenjo-daro: Seal: M-278 a: Jagat Pati Joshi and Asko Parpola, 1987: Corpus of Indus Seals and Inscriptions: Volume 1: Page 68: Collections in India: Suomalainen Tiedeakatemia.
Image Credit:
Indus Script Sign Number 2648: List of Sign Variants: Iravatham Mahadevan, 1977: The Indus Script: Texts, Concordance and Tables: The Director General Archaeological Survey of India.