Left tail light out.. both bulbs turn signals still works.. is it a fuse or what.. right side still works.. you replaced both bulbs left side -- still out .. is it a fuse or what Thanks?

The tail light bulb is the bottom one and is a 1157 that has two elements. One element can still operate for the signal but the tail element is broken. Replace this bulb with a new 1157. Fuses don't control left or right, they control both together. Fuse goes, both go. Check pigtail for corrosion (white looking powdery substance) and clean it if needed, and check for voltage at the pigtail. If no voltage, trace wiring from bad light socket, toward fuse box, checking every few feet, for voltage, until you get a good voltage reading. From that point, back to the tail light socket, the wire needs to be replaced. Don't forget to check the ground, also.