Sash is a noun.
sash, pane, sill
The bottom wooden part of the window. In this case, the 'sash' is any kind of covering for windows. It could be shutters, a shade, blinds, whatever. Or it could be that the narrator "opened the window".
The noun sash is the singular form. The plural noun is 'sashes'
A waist sash is commonly referred to as a "sash" or "waistband." In specific contexts, it might also be called a "obi" in Japanese fashion or a "belt" when it serves a functional purpose. These garments are often used to accentuate the waistline or as part of traditional attire.
Ned Kelly's green sash is kept at the State Library of Victoria in Australia. It is part of a collection of artifacts related to the infamous outlaw, who wore the sash during his exploits in the late 19th century. The sash is significant as it represents Kelly's defiance and has become an iconic symbol of Australian folklore.
An obi [Japan, female] is part of traditional kimono garb.
The part of speech for this particular word is a noun.
part of speech
The part of speech for "answer" is a noun.
adverb
what part of speech is beneath
The plural of sash is sashes.