mouse  toys意思是老鼠玩具
解释如下:在英语中,名词修饰名词的时候,一般用单数。如,苹果树apple tree,橘子树orange  tree, 女老师woman  teacher,男老师man  teacher。我的院子里有一棵苹果树,There is an apple tree in my  yard.我是一名女老师I  am a woman teacher.
是mouse toys,因为这是名词作定语,且名词常用单数。中文意思是,老鼠玩具
你把可以扔掉的老鼠玩具挑出来,好吗Could you sort out the mouse toys that can be thrown away?
该托儿所明亮宜人,有许多老鼠玩具。The nursery is bright and cheerful, with plenty of mouse toys.