I use a popular VPN. If I travel, can my laptop be "seen" if I use public wi-fi?

Your laptop can still be "seen" if you're on a network and someone is monitoring it. The VPN connection will encrypt your network traffic from your laptop. Anyone monitoring the network can see that you're using a VPN connection, but they won't be able to see what you're doing.

Most of the cases VPN can hide your digital security and privacy, and your laptop might not be “seen” to anyone while traveling.

If it won’t work, so what is the benefit of VPN & why VPN providers are claiming that their VPN masked your identity.

When we are connected to the VPN and access the internet, our Internet Service Provider (or the Public Wi-Fi Hotspot) will not able to see what stuffs we do on the internet but our VPN service provider knows about it.

VPN offers privacy, encryption and anonymity, means what things you do with during the VPN connection will remain private and encrypted.

Hence the Middle Men not able to see what stuffs you are performing during the connection.