The Japanese noun '背 (せ)' primarily refers to 'height' or 'stature' of a person. It is commonly used to describe how tall someone is. For example: His height is impressive「彼の背は高い」(かれのせはたかい). Additionally, '背' can also refer to the 'back' of a person or an object, though this usage is less common in everyday conversation. For example: She has a straight back「彼女の背はまっすぐだ」(かのじょのせはまっすぐだ). The word is versatile but most frequently used in the context of physical height.