What does John 17:14 mean?

In praying for the disciples (John 17:6), Jesus has mentioned His prior teachings (John 17:13). These are the "word" which was part of His earthly ministry. Jesus uses the Greek root word logos here; this is the same term John applied to Jesus at the start of this gospel (John 1:1). Jesus is the Logos of God—the message and truth given by God the Father—and part of His mission is to pass along God's words to mankind.

Some of the truths contained in Christ's preaching won't fully make sense until after His death, burial, and resurrection (John 2:22). Others will become clear thanks to the influence of the Holy Spirit (John 16:13–16).

In this context, "the world" means unbelieving, fallen humanity. No one likes to be called out for their failures (John 3:20). That's even more true when moral truth exposes a sinful world (1 Peter 4:4). Christians are called on to influence the world (Matthew 5:13–16), but not to be tainted by it (Romans 12:2; Colossians 2:8; James 1:27). A cornerstone of Christian faith is following the example of Jesus Christ (John 14:15), and the more Christ-like a person is, the more an anti-Christian world will hate and persecute them (John 16:1–4).