To worship is to show a lot of love and adoration for something. Religious believers worship gods, and people can worship other people and things too.
Worship is an extreme form of love — it's a type of unquestioning devotion. If you worship God, then you love God so much that you don't question him at all. Going to church is a form of worship — so is prayer. People also use the word worship in other cases. If you love a musician or sports star, you might say, "I worship her!" Or someone might say to you, "Man, you need to wake up and stop worshiping him."