Transport Layer Security (TLS) is a protocol that provides privacy and data integrity between two communicating applications.

Microsoft SQL Server now supports TLS 1.2 protocol. TLS stands for Transport Layer Security. It is a certificate used for data encryption over network.

TLS is an advance version of SSL.

More info can be found on https://blogs.msdn.microsoft.com/sqlserverfaq/2012/04/04/can-tls-certificate-be-used-for-sql-server-encryption-on-the-wire/