In this Indus sign, the adult person holds both the body of a cart and a pack. Hence, it is the phrase 'both carters and caravanners'.
Illustrative Text Reference:
Harappa: Stone Object: H-1506 A: Asko Parpola, B. M. Pande, and Petteri Koskikallio, 2010: Corpus of Indus Seals and Inscriptions: Volume 3,1: Page 202: New material, untraced objects, and
collections outside India and Pakistan: Suomalainen Tiedeakatemia.
There is only one extant example of this Indus sign.
Indus Script Sign Number 33: Sign List of the Indus Script: Iravatham Mahadevan, 1977: The Indus Script: Texts, Concordance and Tables: The Director General Archaeological Survey of India.