Viruses can steal money, destroy files, & spy on what we do. Keeping software updated and using antivirus helps keep them away.
WiFi is how your devices are able to connect to the internet without wires. This can often be a weak spot for security.
Often it's not the computer we care about but the data on it. Take regular backups & learn to securely destroy old equipment.
It's easy to think that cyber security is only for computers, but mobile devices have some unique security requirements too.