This is a pictograph of a container with a narrow neck, which would have been used for storing liquids. It is the symbol for the noun vase.
Illustrative Text Reference:
Mohenjo-daro: Seal: M-28 a: Jagat Pati Joshi and Asko Parpola, 1987: Corpus of Indus Seals and Inscriptions: Volume 1: Page 16: Collections in India: Suomalainen Tiedeakatemia.
Image Credit:
Indus Script Sign Number 1298: Sign List of the Indus Script: Iravatham Mahadevan, 1977: The Indus Script: Texts, Concordance and Tables: The Director General Archaeological Survey of India.