This is the noun house to which a stylised right hand has been added (the hand is shown in profile). In most people the right hand is the dominant hand. The dominant hand is the most skilful hand
and is associated with the performance of tasks. In this instance, it signifies help. Hence, this Indus sign is an ideograph for an assistant's or an associate's house, home or dwelling place.
Illustrative Text Reference:
Mohenjo-daro: Seal: M-134 a: Jagat Pati Joshi and Asko Parpola, 1987: Corpus of Indus Seals and Inscriptions: Volume 1: Page 44: Collections in India: Suomalainen Tiedeakatemia.