Philippians 2:7 might be the most difficult verse to explain simply, but following it, verse 8 is as simple and straightforward as it can be.

And being found in human form, he humbled himself by becoming obedient to the point of death, even death on a cross.

Philippians 2:8 (ESV)

Christ Jesus, being God, became a man, and if that wasn’t enough self-humbling, He added to His human life the reality of a human death, and if that wasn’t enough self-humbling, He took the most despised of deaths, dead by crucifixion.

That is the simple explanation of the verse. The implication of it has already been stated in verses 3-5. If Jesus did verse 8, ought you and I not to do verse 3?

Do nothing from selfish ambition or conceit, but in humility count others more significant than yourselves.

Philippians 2:3 (ESV)

And verse 4?

Let each of you look not only to his own interests, but also to the interests of others.

Philippians 2:4 (ESV)

Thankfully, according to verse 5, we who are in Christ, can do so!

Have this mind among yourselves, which is yours in Christ Jesus,

Philippians 2:5 (ESV)