A Responsible Person is a legal or natural person based in either the UK or EU who will act as the unique representative for your product(s) in that respective region.
Commonly referred to as ARP (Amazon Responsible Person), it is a legal requirement as part of UK and EU product and labeling compliance responsibilities that requires having the address and point of reference for a specific economic operator as the legal point of contact of your products.
Depending on which EU/UK regulation the product is identified as will determine which set of rules, supporting documents, and requirements are needed.