What does Matthew 15:1-28 really mean?

¹ Then Pharisees and scribes came to Jesus from Jerusalem and said,
² “Why do your disciples break the tradition of the elders? For they do not wash their hands when they eat.”
³ He answered them, “And why do you break the commandment of God for the sake of your tradition?
⁴ For God commanded, ‘Honor your father and your mother,’ and, ‘Whoever reviles father or mother must surely die.’
⁵ But you say, ‘Whoever tells his father or his mother, “Whatever you would have gained from me is a gift for God”—
⁶ he need not honor his father. So for the sake of your tradition you have made void the word of God.
⁷ You hypocrites! Well did Isaiah prophesy of you, when he said:
⁸ “‘This people honors me with their lips,
but their heart is far from me;
⁹ in vain do they worship me, teaching as doctrines the commandments of men.
¹⁰ And he called the people to him and said to them, “Hear and understand:
¹¹ it is not what goes into the mouth that defiles a person, but what comes out of the mouth; this defiles a person.
¹² Then the disciples came and said to him, “Do you know that the Pharisees were offended when they heard this saying?”
¹³ He answered, “Every plant that my heavenly Father has not planted will be rooted up.
¹⁴ Let them alone; they are blind guides. And if the blind lead the blind, both will fall into a pit.
¹⁵ But Peter said to him, “Explain the parable to us.”
¹⁶ And he said, “Are you also still without understanding?
¹⁷ Do you not see that whatever goes into the mouth passes into the stomach and is expelled?
¹⁸ But what comes out of the mouth proceeds from the heart, and this defiles a person.
¹⁹ For out of the heart come evil thoughts, murder, adultery, sexual immorality, theft, false witness, slander.
²⁰ These are what defile a person. But to eat with unwashed hands does not defile anyone.”
²¹ And Jesus went away from there and withdrew to the district of Tyre and Sidon.
²² And behold, a Canaanite woman from that region came out and was crying, “Have mercy on me, O Lord, Son of David; my daughter is severely oppressed by a demon.”
²³ But he did not answer her a word. And his disciples came and begged him, saying, “Send her away, for she is crying out after us.”
²⁴ He answered, “I was sent only to the lost sheep of the house of Israel.”
²⁵ But she came and knelt before him, saying, “Lord, help me.”
²⁶ But he answered, “It is not right to take the children’s bread and throw it to the dogs.”
²⁷ She said, “Yes, Lord, yet even the dogs eat the crumbs that fall from their masters’ table.”
²⁸ Then Jesus answered her, “O woman, great is your faith! Be it done for you as you desire.” And her daughter was healed instantly.