GlassWire Alerts Dictionary explains what its alerts mean

RDP Connection Detection

Detect RDP (Remote Desktop Protocol Connections) where someone may be fully accessing your PC or server's desktop and may have full control of that machine.
WiFi Evil Twin Alert

Know when new hardware comes online that uses the same WiFi network name you’re currently using. This feature helps you avoid “evil twin” attacks where a separate new WiFi network is made to trick you or your colleagues into connecting to it to monitor your network activity illegally or exploit your device. This alert also tells you when your WiFi network loses its password.
New Application Monitor

Alerts you every time a new unknown application is accessing the Internet or network. Initially you may receive a lot of these alerts immediately after installing GlassWire but they will become rare over time. These alerts are useful because you can see when any new application on your system is suddenly accessing the Internet and investigate the details. It's interesting to see what applications phone home to unknown servers or do things you never expected on the network.
System File Changed

Alerts you to a system file that has changed that is network related. If a network related file is modified it may be a good idea to check it out if you didn't initiate the change yourself.
Device List Change

Alerts you to any network related devices on your system that were changed.
Application info monitor

Alerts you to changes with any applications that access the Internet that could be caused by malware.
While you were away

Gives you a summary of what network activity occurred on your computer while you were away or while your computer was idle.
ARP Spoofing

Looks for and reports ARP spoofing. ARP spoofing may allow an attacker to intercept data, modify your Internet traffic, or stop your traffic all together.
Traffic Monitor

Go to the "Usage" tab and click the "Options" on the left side to set an alert once you hit a certain bandwidth level.
Proxy Monitor

Alert you to proxy use or changes.
DNS settings

Alerts you to DNS changes on your system. Some toolbars or malware can change your DNS settings without your permission. Using unknown DNS servers can be dangerous or cause you to experience annoying ads.
Internet Access Monitor

Alerts you to Internet access changes on your system.
Remote Client Connection

If you enable the remote access feature this alert lets you know when you connect to your server or computer remotely with GlassWire. Remote monitoring is popular with GlassWire users who manage remote servers for work, gaming, etc…
Suspicious Hosts

GlassWire keeps an up to date list of known suspicious hosts and alerts you if you contact one. Suspicious hosts are often related to botnets, malware, and other malicious behavior.
Ask to connect

Allow or deny a new network connection to your computer.
New network device

A new device just joined your network or WiFi.
Other

We may have some other useful security related alerts that we don't list here yet but feel free to ask on helpdesk or forum if you see something and you don't know what it means.