What Does "disc Herniation At L5-S1 Level" On MRI Mean?

hi,ive been experiencing severe lower back pain for many years.I had a L5/S1 microdiscectomy in 1998 with some success but gradually over the past 12 months pain has returned,also resulting in left sided sciatica.A recent MRI shows a L5/S1 Left paracentral disc herniation which indents the traversing left s1 nerve root.There is effacement of the fat plane between the disc and the S1 nerve root.

What does this mean and is physiotherapy going to be enough to resolve this problem or am i going to need another microdiscectomy?