@Pete
A Virtual Private Network (VPN) is essential if connecting to the Internet from a cafe, train, bus, airport, hotel or similar, because these are unprotected networks and naughty people can eavesdrop on your communications, steal your passwords and generally create havoc.
Of course this doesn't happen every day in every situation; but certainly often enough to demand the extra security of a VPN.
My advice would be to avoid "free" VPNs and go for one of the top ten VPNs for which you have to pay.
This may help you:
Popular VPNs Compared | Other World Computing Blog
In answer to your questions: You can use a VPN on any device that communicates with the Internet - Macs, iPhones, iPads.
Once you purchase a VPN, an app bearing that name will be on all your devices. You don't need to worry about your home Wi-Fi, your travel arrangements. Once activated, you can select where in the world you want to be from the list of sites provided by the VPN app.
All you really need to know - certainly at the beginning - is that it disguises your ISP address and identity.
And please don't feel embarrassed at asking these questions. Not only are we here for that purpose; but most of us started out in a similar situation to you.
Ian
