Reddit – Dive into something

I’ve to debate the graph linked under. It’s a Producer Worth Index by Commodity: Farm Merchandise: Eggs for Recent Use. My essential query is what is strictly the Y axis is? It’s labeled “Index Dec 1991=100”, I’ve tried wanting into it however can not seem to discover a easy clarification. Additionally is that this graph adjusted for inflation? Lastly it says it isn’t seasonally adjusted, what does this imply and what have an effect on would it not have on the graph if any?

https://fred.stlouisfed.org/sequence/WPU017107#0

Thanks for the assistance! Wanting ahead to studying extra about commodities on this group!