What does Romans 15:2 mean?

Paul has written in the previous verse that those who are strong in their Christian faith, fully convinced of the grace of God and their individual freedoms in Christ, should not insist on pleasing themselves at the expense of other Christians.

Now he puts it positively: Strong Christians should make it higher priority to please others for their good than to please themselves. They should take on the mission of building up their neighbors. This echoes what Paul wrote in Romans 12:10: that living-sacrifice Christians must outdo each other in showing honor. To put it another way, they must honor each other above themselves.

This is an application of what Jesus called the greatest commandment among human relationships (Matthew 22:35–40). Loving our neighbors as we love ourselves means putting their "pleasing," or satisfaction, or good outcome above achieving our own good outcome. It's a lifestyle of sacrificing what I want, to give to others what they want, for their good and growth.