Jesus claims to be THE way, THE truth, and THE life, insinuating that there is NO other way, truth or life.
Jesus says that He is the way. The way to what? In John 14:2-4, Jesus says to His disciples, "In my Father's house are many rooms. If it were not so, would I have told you that I go to prepare a place for you? (3) And if I go and prepare a place for you, I will come again and will take you to myself that where I am you may be also. (4) And you know the way to where I am going." Thomas replies that he doesn't know where Jesus is going, how can he know the way, and Jesus said:
I AM THE WAY.
There is one way. Jesus is the way to His Father's house. Thus, Jesus is the way to eternal life with Himself and the Father. Prior to this scenario with His disciple's, Jesus had mentioned that He was the only way. In John 10:9, Jesus says "I am the door. If anyone enters by me, he will be saved and will go in and out and find pasture."
By saying that He is the door for the sheep, Jesus says that He is THE WAY in. He is the entrance into a fold that contains 'proper pasture.' Some Near Eastern shepherds slept in the gateway of the fold in order to guard their sheep. This is how Jesus shows Himself.
Jesus also calls Himself the truth. In this, He is somewhat reiterating that He is THE true way to the Father. By being The truth, He is also conveying that He is the ONLY truth. There aren't more options of truth that allow you to be able to pick whichever one pleases you most. He is the only truth.
"I am the life." He alone holds the power to life. He is the way to life and life to the full (John 10:10). He offers a new life for His people and an eternal life in heaven. In John 11:25, He says "I am the resurrection and the life. Whoever believes in me, though he die, yet shall he live."