This ideograph combines a profile of the right hand with a pair of hands. A pair of hands at your right hand is a trusted helper. Hence, Mahadevan's sign number 4223 is the noun friend.
Illustrative Text References:
Mohenjo-daro: Seal: M-842 a: Sayid Ghulam Mustafa Shah and Asko Parpola, 1991: Corpus of Indus Seals and Inscriptions: Volume 2: Page 76: Collections in Pakistan: Suomalainen Tiedeakatemia.
Mohenjo-daro: Seal: M-1741 a: Asko Parpola, B. M. Pande, and Petteri Koskikallio, 2010: Corpus of Indus Seals and Inscriptions: Volume 3,1: Page 37: New material, untraced objects, and collections outside India and Pakistan: Suomalainen Tiedeakatemia.
Image Credit:
Indus Script Sign Number 4223: List of Sign Variants: Iravatham Mahadevan, 1977: The Indus Script: Texts, Concordance and Tables: The Director General Archaeological Survey of India.