What is a parable?
A parable is a story that teaches us something about God, his kingdom, and ourselves. The stories are often quite simple, but they have an underlying meaning, so sometimes they can be a bit confusing, and hard to understand.
Why did Jesus teach in parables?
Matthew 13:11-16 gives us the answer. Jesus quotes from Isaiah 6:8-9
"He replied, "The knowledge of the secrets of the kingdom of heaven has been given to you, but not to them. Those who have will be given more, and they will have an abundance. As for those who do not have, even what they have will be taken from them. This is why I speak to them in parables:
“Though seeing, they do not see; though hearing, they do not hear or understand. In them is fulfilled the prophecy of Isaiah: “‘You will be ever hearing but never understanding; you will be ever seeing but never perceiving. For this people’s heart has become calloused; they hardly hear with their ears, and they have closed their eyes. Otherwise they might see with their eyes, hear with their ears, understand with their hearts and turn, and I would heal them.’ But blessed are your eyes because they see, and your ears because they hear."
Jesus teaches in parables to separate those who have "ears" and those who don't. The use of the word "ears" is another way of saying "those who want to know about God's kingdom". Those who want to learn from Jesus will be able to understand what these parables are saying because the knowledge of the secrets of the Kingdom of Heaven have been given to them. But those who do not want to know about God's kingdom or learn from Jesus just won't get it... even what they know will be taken away from them, so that even though they have ears - they won't be able to hear; and even though they have eyes - they won't be able to see... because they have hardened their heart against Jesus.
Not everyone wants to hear
This is a hard teaching, but we can see the truth of it. Why is it when we tell our friends about how much God loves them and how much Jesus cares for them, they just don't get it? It's because the do not want to know about God's kingdom, they do not want to learn from Jesus. This doesn't mean that we shouldn't bother telling them about God's kingdom and king Jesus (Jesus persisted in teaching those who wanted to hear and those who didn't), but it does mean we shouldn't be surprised when people seem to miss the good news.
Parables are hard work. But... when we put in the effort to understand them, what we learn about God, his kingdom, and ourselves is truly worth the effort. If you can read the parables of Jesus, learn from them, and be changed by them, then "blessed are your eyes because they see, and your ears because they hear." The secrets of the kingdom of God have been given to you.