Question
Okay this past monday I had an MRI of my lower back... but I have no idea what this all means, and my orthapidic doctor explained some but im still kinda lost

Noncontrast MRI of the lumbar spine

Findings: 5 lumbar vertebral bodies assumed. Normal conus. Normal lumbar alignment. Normal bone marrow signal

L1 through L4 intervertebral disks are negative

L5-S1: Disk degeneration and desiccation with broad-based posterior disk bulging and moderate size central disk protrusion. Tere is evidence of posterior annular tearing. Mild facet and ligamentum flavum hypertrophy is also present. There is moderate central stenosis with probable mass effect upon the traversing S1 nerve roots in the lateral recesses. Minimal bilateral neural formainal narrowing of doubtful significance.

Impression: Evidence of posterior annular tearing L5-S1 with broad-based posterior disk bulging and superimposed moderate size central disk protrusion. There is mild cental canal stenosis L5-S1 with significant narrowing of the lateral recesses and probable mass effect upon the traversing S1 nerve roots

Answer
Although I'm not a physician or surgeon, I can tell you that the impression says you have a disk degenerating between your 5th lumbar vertebra and your 1st sacral vertebra in your low back.  

It also states that there is a ring-like tear in the rear of the disk (toward your back) with the disk bulging out to the rear and also around the vertebral space in general.

It further says that you also have a narrowing of the opening in the middle of the vertebra; that's where your spine runs through the bone.  It also states that the narrowing is present in the area where the nerves leave the spine.

Thank you for your question, Allen.  I hope that my answer was helpful.