I'm trying to replace a ceiling light fixture but the wires are different
The symbol you described sounds like ground:



This should connect to the bare wire in your box. All white wires together, all green/bare ground wires together, and the black/L wire to the black wire in the box.

If your fixture has both a bare copper wire and a green insulated one, the green may be to connect different pieces of the fixture. Check the instructions, perhaps it should be bonded to another point on the fixture rather than to the supply wiring.

Finally, do not wrap your ground wire around the other wires in your box. Ground should be kept separate, you don't want to inadvertently have it contact the hot wire (instant short) or neutral (a hard-to-detect failure of the safety ground).