This passage from Revelation discusses Jesus' second coming. It states that:
1) Jesus' coming is a reality, as he promises "I am coming quickly" multiple times. 
2) While the timing of his return is unknown, he instructs believers to always watch and be ready, since he will come unexpectedly like a thief in the night.
3) Believers should keep Jesus' words and commandments so that they may enter heaven when he returns.