Nevertheless to remain in the flesh is more needful for you.
Philippians 1:23-24 (NKJV)
Normally when we do something, we are doing something that we like, that in some way will benefit us. Most people would not do something that they do not like to do, or get no benefit from, unless they were doing something that had the specific goal of benefiting someone else. We can do things that are strictly for our benefit, or we can do something that will bring a benefit to someone else, which may somehow also benefit us, but what we do will often be better for one person than it is for another.
When Paul wrote his letter to the Philippians, he was in prison, and Paul talked about how he desired to leave this world to go and be with Jesus, which, as he said, would be far better. But Paul said that while he wanted to leave here, which would be better for him, Paul understood that it would be better for the people in the church in Philippi if he stayed. If Paul left this world to be with Jesus, that would be great for Paul, but he would no longer be in a position to help the Philippians.
Paul wrote in Philippians 1:21 that to live is Christ, but to die is gain, but Paul also said it was better for the people at Philippi if he stayed with them and did not leave this world. Paul based his decision about what to do on what was better for those people and not what was better for himself. Rather than just focusing on doing what we want that is just for our benefit, we should be the kind of people who prefer others before ourselves and do what is better for them. This is the attitude that Paul had, that we see in the life of Jesus, and it is the way we need to live too.