This is the 7487th most frequent Chinese word.
解下
"解下" means "to take off" or "to remove."
In this sentence, '解下' means to unfasten or remove an item (the coat) from one's body.
他将自己的外套解下来挂在衣架上。
He took off his coat and hung it on the coat rack.
Here, '解下' refers to attempting to untie or release (the knot).
我不能解下那结，它卡得太紧了。
I cannot untie that knot; it is too tight.
This usage of '解下' reflects the action of detaching or removing (the picture frame) from its position.