Keep sensitive info out of your email & chat logs.
A one-time secret is a link that can be viewed only one time. A single-use URI.
When you send people sensitive info like passwords and private links via email or chat, there are copies of that information stored in many places. If you use a one-time link instead, the information persists for a single viewing which means it can't be read by someone else later. This allows you to send sensitive information in a safe way knowing it's seen by one person only. Think of it like a self-destructing message.