This is a pictograph of a mat with each short edge split into six units. It therefore denotes a floor or pitch area with a size of six standard mats.
Illustrative Text Reference:
Mohenjo-daro: Seal: M-1103 a: Sayid Ghulam Mustafa Shah and Asko Parpola, 1991: Corpus of Indus Seals and Inscriptions: Volume 2: Page 116: Collections in Pakistan: Suomalainen Tiedeakatemia.
Comment:
There is only one extant example of this Indus sign. The pitch would have been relatively large. Inscription M-1103 tells us that the pitch was used for oiling wheels. Hence, we can infer that the pitch was big enough to take at least one cart.
Image Credit:
Indus Script Sign Number 1337: List of Sign Variants: Iravatham Mahadevan, 1977: The Indus Script: Texts, Concordance and Tables: The Director General Archaeological Survey of India.