SSL termination is the process of handling SSL encryption/decryption process at the edge of the network. It is commonly used in reverse proxies or load balancers to centralize all SSL communication in a single component. The load balancer keeps the SSL certificate and does all encryption and decryption of traffic, while the actual servers handle only plain HTTP traffic to and from the load balancer.
Overall, this approach reduces the CPU load on servers (because they don’t need to handle SSL encryption), and makes managing the SSL certificates easier for multiple services.
References
https://www.haproxy.com/glossary/what-is-ssl-tls-termination