Image: Iravatham Mahadevan
Image: Iravatham Mahadevan

This is the noun time with the addition of a ruler. The ruler has two spaces, which translates as two hours.

You should note that the ruler has a straight edge which indicates a precise measurement. This symbol refers to exactly two hours.

Illustrative Text Reference:

Harappa: Tablet: H-208 A: Jagat Pati Joshi and Asko Parpola, 1987: Corpus of Indus Seals and Inscriptions: Volume 1: Page 213: Collections in India: Suomalainen Tiedeakatemia.

Image Credit:

Indus Script Sign Number 1401: List of Sign Variants: Iravatham Mahadevan, 1977: The Indus Script: Texts, Concordance and Tables: The Director General Archaeological Survey of India.