This is a pictograph of a slope. Hence, it is the noun slope.
Illustrative Text Reference:
Kalibangan: Tablet in bas-relief: K-69 A: Jagat Pati Joshi and Asko Parpola, 1987: Corpus of Indus Seals and Inscriptions: Volume 1: Page 312: Collections in India: Suomalainen Tiedeakatemia.
Image Credit:
Slope: Lynn Fawcett, 2020.