This is a pictograph of a measuring rod. There are seven spaces which gives us seven units of measurement. However, you should note that the marks between the spaces are diagonal rather than horizontal. This indicates that the measurement is estimated rather than precise. Therefore, the suggested translation for Mahadevan's sign number 1118 is 'roughly seven units'.
Illustrative Text Reference:
Chanhu-daro: Seal: The Cleveland Museum of Art: The J. H. Wade Fund 1973.160: http://www.clevelandart.org/art/1973.160: Accessed: 26 February 2018.
Image Credit:
Indus Script Sign Number 1118: List of Sign Variants: Iravatham Mahadevan, 1977: The Indus Script: Texts, Concordance and Tables: The Director General Archaeological Survey of India.