Explanation
A DNS SAN (Subject Alternative Name) is an extension of the X.509 certificate standard that allows specifying additional hostnames or IP addresses that the certificate can be used for. A DNS SAN is useful for validating the identity of the server or client that presents the certificate, especially when the common name (CN) field does not match the hostname or IP address of the server or client.
In this case, the certificate has a CN of mc41.site94.example.com, which is the fully qualified domain name (FQDN) of the standalone Aruba Mobility Controller (MC). However, this CN may not match the hostname or IP address that the MC uses for the Web UI or for implementing RadSec with Aruba ClearPass Policy Manager. For example, if the MC uses a different FQDN, such as mc41.example.com, or an IP address, such as 192.168.1.41, for these purposes, then the certificate would not be valid for them. Therefore, the certificate should have a DNS SAN that includes all the possible hostnames or IP addresses that the MC may use for the Web UI and RadSec.

Explanation
A custom NAE script is a Python script that defines the monitors, the alert-trigger logic, and the remedial actions for an NAE agent. A monitor is a URI that specifies the data source and the data type that the NAE agent should collect and analyze. For example, to monitor the ARP inspection statistics on a VLAN, the monitor URI would be something like this:

where <vlan-id> is the ID of the VLAN to be monitored.
To allow the admins to select the correct VLAN ID for the agent to monitor when they create the agent, you need to define a VLAN ID parameter in the NAE script. A parameter is a variable that can be set by the user when creating or modifying an agent. A parameter can be referenced in other parts of the script by using the syntax ${parameter-name}. For example, to define a VLAN ID parameter and reference it in the monitor URI, you would write something like this:

This way, when the admins create or modify the agent, they can enter the VLAN ID that they want to monitor, and the NAE script will use that value in the monitor URI.
You can find more information about how to write custom NAE scripts and use parameters in the NAE Scripting Guide