In Kubernetes, a Secret is an object that stores sensitive information like a password, token, key, etc. One of the several good practices for Kubernetes secret management is making use of a third-party secrets store provider solution to manage secrets outside of the clusters and configuring pods to access those secrets. There are plenty of such third-party solutions available in the market, such as:
HashiCorp Vault
Google Cloud Secret Manager
AWS Secrets Manager
Azure Key Vault
These third-party solutions, a.k.a External Secrets Managers (ESM), implement secure storage, secret versioning, fine-grain access control, audit and logging.