More info about Rendering Options

Hi, where can I get more information about Rendering Options https://prnt.sc/i38jhg
Most of them are pretty clear, but others like "Meta Pass" and "Add Pass" are confusing. I've found some info about Meta Pass but I have no idea what "Add Pass" means. Also, where I can enable light probes? If I want to make lit PBR particles with light probes support.
For example, if I making unlit alpha blended shader, I need to use something like this https://prnt.sc/i38l53 right?
Most of them are pretty clear, but others like "Meta Pass" and "Add Pass" are confusing. I've found some info about Meta Pass but I have no idea what "Add Pass" means. Also, where I can enable light probes? If I want to make lit PBR particles with light probes support.
For example, if I making unlit alpha blended shader, I need to use something like this https://prnt.sc/i38l53 right?