This passage means that we can make plans but God will only let those plans come through if they are within His plans for you. I love this passage because it gives us reasoning for why sometimes even though we pray to God for something it doesn't happen.
Jesus has a funny way of messing up all of your plans to allow room for His to take place. I imagine Him chuckling and saying to me, "These ideas of yours are dreadful. Now let me show you all the beautiful things I have in store for you."