What does mri results mean when they say Spondylotic changes at l3-4 and l4-5?

It refers to undesirable changes in the vertebral bodies and intervertebral discs in your spine. When their quality and alignment deteriorates, your spine's stability and flexibility decrease. These can be caused by injury and aging and can be faster or slower to show up depending on level of physical activity, genetics, nutrition, etc. Usually they are associated with disc compression which may lead to pinching of nerves in your spine.