What happen if I connect to multiple locations on different devices on same vpn account

Those different devices will have different IP right? Is it able to identify they are all the same person?

If your VPN provider allows multiple concurrent devices, and they are all connected to different servers, then no one externally would know they’re associated together in any way.

The VPN provider itself would certainly know though as you’re using the same credentials to authorized all the devices to access the servers.

or we could say, our ISP and VPN knows that this IP address is connecting to different VPN servers?

Agree. The ISP will see your home IP connected to three different endpoints, and it would be trivial for them to know they are VPN servers if it’s a commercial provider.

I was assuming the OP is referring to whatever they’re connecting to on the other side of the VPN gateway… but the question really isn’t clear.

Edit, just noticed you are the OP… so who is the “they” you are asking about?