This is a pictograph of a door or gate. The Indus symbol for a door or a gate is always two Indus units wide. This one is seven Indus units tall.
Illustrative Text Reference:
Mohenjo-daro: Seal: M-25 a: Jagat Pati Joshi and Asko Parpola, 1987: Corpus of Indus Seals and Inscriptions: Volume 1: Page 15: Collections in India: Suomalainen Tiedeakatemia.
Comment:
In inscription M-25, there are two of these symbols side by side, which depict a double door.
Image Credit:
Gate 2 by 7: Lynn Fawcett, 2017.