Do nothing out of selfish ambition or vain conceit, but in humility consider others better than yourselves. Each of you should look not only to your own interests, but also to the interests of others. but made himself nothing, taking the very nature of a servant, being made in human likeness.

What does Do nothing from rivalry or conceit but in humility count others more significant than yourselves mean?

“..in humility count others more significant than yourselves,” means that in order to love others we need to think less about what we think about things, and consider how others are thinking and feeling.

What does vain conceit mean?

excessively proud of or concerned about one's own appearance, qualities, achievements, etc.; conceited: a vain dandy. proceeding from or showing pride in or concern about one's appearance, qualities, etc.; resulting from or displaying vanity: He made some vain remarks about his accomplishments.