The advice of the Apostle Paul in this biblical text is to recommend that we think of all good things, to always give a good impression and a good testimony of being a Christian.
Philippians 4: 8
"8 For the rest, brothers, everything that is true, everything that is honest, everything that is just, everything that is pure, everything that is kind, everything that is of good name; if there is any virtue, if something worthy of praise, think of this."
Nowadays most of the people are always thinking badly about the rest of the people and it is because there is a lot of evil, but we as children of God who are different do not fall into these things; It is quite difficult to achieve this quality in many people, since honesty and sincerity few apply it in their lives, but we as a Christian do apply it.
The just, the pure, the kind all these good things we must think because God pleases us and helps us to be better people every day, not only think it, but also apply it.