The circle is an ideograph for the adverb round.
Illustrative Text Reference:
Kalibangan: Seal: K-40 a: Jagat Pati Joshi and Asko Parpola, 1987: Corpus of Indus Seals and Inscriptions: Volume 1: Page 305: Collections in India: Suomalainen Tiedeakatemia.
Comment:
Please note that the elephant motif on the seal impression K-40 a has its head facing left. Therefore, the inscription is read from left to right.
Image Credit:
Round: Lynn Fawcett, 2018.