The parable of the two sons is about a father who tells his first son to go work in the vineyard. The son says he does not want to, but he winds up working on it anyway. When the father tells his second son to go work on the vineyard, he tells him he will work on it. The second son later chooses not to work in the vineyard.
The significance of this story is that if you are not true to your word than you’re not really a good person. The first son, who does not want to work on the vineyard but winds up helping, represents the people who were non-believers that were sent a message by John the Baptist to believe in God.
These people repented and wound up following God, as shown by the first son deciding to help with the vineyard after saying no. The second son represents the people who have been believers for their entire life. Even though these people have been believers for their entire life they continue to commit sins such as lying.
This parable teaches us about who God will accept into the kingdom of heaven after they have died. God does not care if you have not believed in him at any point in your life. If a person a couple of weeks begins to have faith in God and no longer sins, they are far more welcome in the kingdom of heaven than a person who claims to be a believer but commits horrible sins.
This parable teaches us that God doesn’t want someone like the second son, who claims to be someone that they are not. The first son does not lie and ends up helping in the end, unlike his brother who creates a false image of himself as someone who helps, but in the end he is only letting his father down, which is exactly what God tells us not to do.