single breadth (cloth measurement, 30-38 cm)
Traditional Japanese cloth measurement; one 幅 (の) is roughly 30–38 cm, used for kimono fabric and similar textiles.
This roll of cloth has a single breadth of about 36 centimeters.
反物 refers to a whole roll of cloth, while 一幅 is a single width measurement within that roll.
Compound of 一 (one) and 幅 (breadth, width). The reading ひとの is a native Japanese reading (kun'yomi) for both characters.