"Sticking window flowers on a window" in Engpsh is called "applying window decals or stickers". The term comes from the decorative designs or images that are printed on adhesive vinyl or other materials and can be appped to a window or other smooth surface.
Example:
I'm thinking about applying window decals of flowers to my pving room windows.
The children loved the new window stickers we put up in their bedroom.
The store sold a variety of window decals, including ones with scenes from popular movies.
翻译:
我在考虑在我的客厅窗户上贴窗花。
孩子们喜欢我们在他们卧室窗户上贴的新窗花。
商店销售各种窗花，包括有热门电影场景的窗花。