The SSL certificate has been signed using a weak hash algorithm - SHA-1.
The remote service uses an SSL certificate that has been signed using a cryptographically weak hashing algorithm - SHA-1. This algorithm is known to be vulnerable to collision attacks. In theory, a determined attacker may be able to leverage this weakness to generate another certificate with the same digital signature, which could allow them to masquerade as the affected service.
Configure the service to only allow strong encryption, and replace the certificate if necessary.