Then when you go to take it out it will be all dried out and there’ll just a house full of needles
I do not understand ’ a house full of needles’.
They are talking about evergreen trees, which we use as Christmas trees in our homes. An evergreen tree has needles instead of leaves on its branches. If you cut down a tree like this and keep it in your house, it dries out and all the needles fall off. Therefore, when you remove the tree, the needles fall everywhere, giving you a “house full of needles”.