1. He is afraid of what they might do to him. Bilbo is a hobbit, and hobbits are generally peaceful and non-violent creatures. They do not like conflict or danger, and they prefer to avoid it whenever possible. Bilbo knows that the dwarves are a tough and warlike people, and he is afraid that if he tells them about the Ring, they will try to take it from him by force.
2. He is afraid of what might happen to the Ring if he gives it to them. Bilbo knows that the One Ring is a powerful and dangerous object, and he is afraid of what might happen if it falls into the wrong hands. He is not sure if he can trust the dwarves to use it wisely, and he is worried that they might use it for evil.
3. He is afraid of the responsibility that comes with possessing the Ring. Bilbo knows that the One Ring is a burden, and he is not sure if he is strong enough to bear it. He is afraid that if he tells the dwarves about the Ring, they will expect him to lead them on their quest to reclaim the Lonely Mountain, and he is not sure if he is willing to do that.
4. He is not sure what the Ring is or what it can do. Bilbo does not know much about the One Ring, and he is not sure what it is capable of. He is afraid that if he tells the dwarves about the Ring, they will ask him questions that he cannot answer, and he will look foolish.
5. He is not sure if he wants to keep the Ring. Bilbo is torn between his desire to possess the Ring and his fear of its power. He is not sure if he wants to keep the Ring for himself, and he is afraid of what might happen if he gives it away.
Whether or not Bilbo's decision to keep the Ring secret from the dwarves is considered lying is a matter of opinion. Some people would say that it is lying because Bilbo is intentionally withholding information from his companions. Others would say that it is not lying because Bilbo does not owe the dwarves any information about the Ring. Ultimately, it is up to each individual to decide whether or not they consider Bilbo's actions to be lying.