This is the noun street corner, to which the scribe has added an aerial view of two walls. It is an ideograph for a walled corner pitch. The size of the pitch in Indus units is given by the number of bricks in the wall. Hence, this corner pitch has the dimensions two Indus units by two Indus units.
Illustrative Text Reference:
Harappa: Seal: H-441 a: Sayid Ghulam Mustafa Shah and Asko Parpola, 1991: Corpus of Indus Seals and Inscriptions: Volume 2: Page 274: Collections in Pakistan: Suomalainen Tiedeakatemia.
Image Credit:
Indus Script Sign Number 1471 (Street Corner Pitch 2 * 2): List of Sign Variants: Iravatham Mahadevan, 1977: The Indus Script: Texts, Concordance and Tables: The Director General Archaeological Survey of India.