The screenshot shows the threat log which records the traffic that matches a threat signature or is blocked by a security profile. The log entry indicates that the traffic was allowed by the security policy rule "Allow-All" but was denied by the vulnerability protection profile "strict" as a threat. The threat name is "Microsoft Windows SMBv1 Multiple Vulnerabilities (MS17-010: EternalBlue)" and the action is "reset-both" which means that the firewall reset both the client and server connections. Reference: : https://docs.paloaltonetworks.com/pan-os/10-2/pan-os-admin/monitoring/use-syslog-for-monitoring/syslog-field-descriptions/threat-log-fields

Decryption Broker is a feature that allows you to use a Palo Alto Networks firewall as a decryption broker for other security devices in your network1. It works by decrypting traffic on one interface and forwarding it to another interface where it can be inspected by other devices before being re-encrypted and sent to its destination2. The firewall acts as a transparent bridge between the two interfaces and does not change the source or destination IP addresses of the traffic2.
To configure Decryption Broker, you need to assign decryption forwarding interfaces (DFIs) to the virtual router that routes the traffic that you want to inspect. The DFIs are used to forward decrypted traffic from one interface to another in a security chain3. A security chain is a set of devices that perform different security functions on the same traffic flow3. You can have multiple security chains for different types of traffic or different segments of your network3.
The reason why you need to assign DFIs to the virtual router that routes the traffic is because Decryption Broker uses routing tables to determine which DFI belongs to which security chain and how to forward traffic between them2. If you assign DFIs to a different virtual router than the one that routes the traffic, Decryption Broker will not be able to find them or forward traffic correctly2.

According to the documentation, not-applicable means that the Palo Alto device has received data that will be discarded because the port or service that the traffic is coming in on is not allowed, or there is no rule or policy allowing that port or service. This occurs because the traffic was dropped or denied before the application match could be performed. Reference: 1 Not-applicable in Traffic Logs - Palo Alto Networks 2 Not-Applicable, Incomplete, Insufficient Data in the Application Field - Palo Alto Networks
https://knowledgebase.paloaltonetworks.com/KCSArticleDetail?id=kA10g000000ClspCAC

Reference:
https://www.paloaltonetworks.com/resources/videos/how-to-run-a-bpa

Adding a WildFire subscription can improve the security posture of the organization by providing protection against unknown malware in near real-time. With a WildFire subscription, the firewall can forward various file types for WildFire analysis, and can retrieve WildFire signatures for newly-discovered malware as soon as they are generated by the WildFire public cloud or a private cloud appliance. This reduces the exposure window and prevents further infection by the same malware. Reference: https://docs.paloaltonetworks.com/wildfire/9-1/wildfire-admin/wildfire-overview/wildfire-subscription