A firewall is a security system that controls incoming and outgoing network traffic based on predetermined security rules. A firewall solution is a set of tools or software that is used to implement and manage a firewall. 

Firewalls are an essential component of a network security strategy and are used to protect against external threats such as malware, hackers, and unauthorized access to network resources. They work by examining incoming and outgoing traffic and blocking or allowing it based on a set of rules. These rules can be based on a variety of factors, such as the source or destination of the traffic, the type of traffic, or the port number being used. 

There are many different types of firewall solutions available, including hardware firewalls, software firewalls, and cloud-based firewalls. The specific solution that an organization chooses will depend on its needs and the nature of its network and systems.