"Our butterfly curtains couldn't fix" is not correct English. Fix needs a direct object. e.g. I fixed the curtains.
The speaker probably means that the curtains don't match, or don't meet in the middle of the window normally. They are my best guesses.
The second sentence is an aphorism, an expression which explains a general idea about life. If you go into an empty room, you can have a positive attitude and do anything you want there. There is nothing in it which is limiting you. For example, you can decorate it how you like, or you can do any activity you like.