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 five marks giving four spaces, which translates as 'around four hours'.
Illustrative Text Reference:
Harappa: Seal: H-132 a: Jagat Pati Joshi and Asko Parpola, 1987: Corpus of Indus Seals and Inscriptions: Volume 1: Page 198: Collections in India: Suomalainen Tiedeakatemia.
Comment:
There is only one extant example of this Indus sign.
Image Credit:
Around Four Hours: Lynn Fawcett, 2018.