What Does Central Posterior Disc Bulge At 14/5 Indents In Thecal Sac Mean?

I could barely walk and struggled to sleep because of lower back pain that went to my leg so i got a scan done after a couple months of struggling. It came back saying i have a central posterior disc buldge at l4/5 indents the thecal sac. What does this mean? What could be a cause and how can i fix this? Also it says i have a minor facet joint degenerative changes at l5/s1. My job requires high levels of manual labour is this going to get worse? Thanks for any advice or guidance, Zlatan