Hey @monkeysloth
You can consider this the place to direct players to when looking at Resistant on the Hellfire Armor, the Burning Man or anyway else for that matter.
The icon (be it On Fire, Poisoned etc) within the symbol indicates the Condition that the model is Resistant to. You can always tell a Resistant symbol apart from a normal Condition symbol as the Resistant symbol will have half of the circle coloured in a grey/green colour.
As for what Resistant does, I’m just going to use the defintion from the Burning Man post as I think it sums up all of this well;
The symbol means that character is resistant to the condition in question. This would mean at the point you would normally suffer that condition, you flip the Luck token - on the Clover Side, you don’t suffer the side effects. On the other side, you suffer the effects as normal.