One of the best ways of interpreting the Bible is to let it speak for itself. The best way to do this is to pay attention to the context in which a word or phrase occurs. Most of the time, that will be sufficient to discover the meaning of the word or phrase in question.
If you look at this sentence in Philippians 2 in context, you will realize that the "mind of Christ" is one of humility, loving service, and obedience. We are to esteem others better than ourselves, we are to serve our brothers and sisters in Christ. Finally, Jesus, who like Adam before him, was created in the "form of God" did not, unlike Adam, think equality with God was a thing to be grasped - as Adam and Eve grasped the forbidden fruit believing the false promise that they would, upon eating the fruit, "be like God." [see Genesis 3:1-6; Philippians 2:6 - NIV; NRSV; ESV]
This mind which Paul says we, by God's grace, must develop is one which obeys the will of God first of all and seeks to humbly bear the burden of others, just as the Lord did and continues to do.
I hope you have found this helpful.