If you didn't have bones, you would be a sack of organs that moved like a worm. Bones have two primary purposes in your body. Some provide structure like the backbone that allows you to stand up tall and straight. Other bones are protective which means that they guard the soft delicate inside parts of your body. Good examples of protective bones are your ribcage that protects your heart and lungs and your skull, which acts like a helmet for your brain.
Bones also have two other important functions, movement and collection of minerals.
Your bones are storage centers for certain minerals, most importantly calcium and phosphate. In movement, skeletal muscles are attached to bones and use the bones as levers to move the body and all of its parts. Your legs allow you to walk and your arms are used to pick up things and carry them. Take a moment and look at your arm. Try to imagine the muscles in your arm and hand manipulating the bones to make them move when working to type on your computer or to move the mouse.