This is the noun time with the addition of some marks from a ruler. There is no straight edge, which implies that the ruler itself is missing. Therefore, this is a symbol for an approximate value. There are three marks giving two spaces, which translates as 'around two hours'.
Illustrative Text References:
Harappa: Seal: H-146 a: Jagat Pati Joshi and Asko Parpola, 1987: Corpus of Indus Seals and Inscriptions: Volume 1: Page 201: Collections in India: Suomalainen Tiedeakatemia.
Mohenjo-daro: Seal: M-1683 a: Asko Parpola, B. M. Pande, and Petteri Koskikallio, 2010: Corpus of Indus Seals and Inscriptions: Volume 3,1: Page 14: New material, untraced objects, and collections outside India and Pakistan: Suomalainen Tiedeakatemia.
Image Credit:
Indus Script Sign Number 1051: List of Sign Variants: Iravatham Mahadevan, 1977: The Indus Script: Texts, Concordance and Tables: The Director General Archaeological Survey of India.