Non-repudiation is the assurance that someone cannot deny the validity of something. Non-repudiation is a legal concept that's widely used in information security and refers to a service, which provides proof of the origin and integrity of data. In other words, non-repudiation makes it very difficult to successfully deny who/where a message comes from, as well as the authenticity and integrity of that message.
Digital signature solutions(combined with other measures) can offer non-repudiation when it comes to online transactions. It's crucial to ensure that a party to a contract or a communication can't deny the authenticity of their signature on a document or when sending the communication in the first place. In this context, non-repudiation refers to the ability to ensure that a party to a contract or a communication must accept the authenticity of their signature on a document or the sending of a message.