The Jewish leaders did not want to believe Jesus. They also did not want the people to believe in him. They constantly followed him around and made trouble for him. They at times accused him of wrongdoing. They tried asking him difficult questions to make him look uneducated. But nothing they did produced the result they wanted.
In John 5:39-40, we read, “Search the scriptures; for in them ye think ye have eternal life: and they are they which testify of me. And ye will not come to me, that ye might have life.” Jesus is telling the Jewish leaders that all they have to do is search the Scriptures. The Old Testament Scriptures have many prophecies regarding the Christ. Jesus is telling them that if they will simply look at his life and look at the Scriptures, they will see that he is indeed the Messiah.
The Jewish leaders believed that eternal life came from the Scriptures. They were partially correct. Eternal life comes to those who obey the Scriptures. The Jewish leaders had come to the point that they believed just possessing the Scriptures was enough. But Jesus is saying that they must study them and obey them.
Jesus was prophesied to come. And the Jews were commanded to listen to the Messiah when he came into the world. The Jewish leaders were refusing to do that.
Keep reading and studying your Bible. Learn all you can from it. Then obey the commandments of God. And if any of this is hard to understand, ask an adult to help you.