There are two distinctive ways to use VPN.
The first, the traditional use, is make your remote computer appear to be on your LAN. Thus “Virtual Private Network”. Commonly used by businesses to allow employees to access their work networks from home or on the road. Can also be used to access home network while on the road. This use is entirely noncontroversial.
All communication is encrypted, which is important for businesses. In addition all traffic can be routed through the work/home LAN, so all communication is protected from snooping when using a public Wifi, although snooping is still possible from the the work/home LAN going outward through the ISP. This gives the same public Wifi protection one gets with VPN services at essentially no cost.
Now days most mentions of VPN is for services which gives encrypted communication to the VPN service provider and, frankly, unknown protection beyond that. Potentially more convenient but more costly than running a home VPN server. Depending on your paranoia level you might want to use the VPN service at home if you suspect your ISP is watching your traffic (as some apparently do!). Note that it’s not stealth – the ISP will know you are using a VPN service.
Note that some internet services (such as HTTPS, ssh, most cloud services) are already safe. Email is about as safe as a postcard even if the connection to the server is encrypted.
That said, I don’t send anything of importance without an encrypted service, and I use a home VPN to access the home network when away. I personally don’t see a need for a VPN service.