Security is fine with most any VPN. Privacy? Be careful which VPN provider you decide to use; research their history and their ownership.
Encryption via HTTPS even through an VPN connection won’t protect your privacy as far as logs showing how you us the VPN go if that service logs activity and shares it with others.
You ask this:
“But I am very worried if the VPN is secure or not.”
Gronostaj states this in his answer:
“All data you send, such as banking details, passwords etc. are encrypted by HTTPS if the website is using it.”
Both of you are 100% correct in each of your points of view. You are right to be concerned about security on VPNs and Gronostaj is correct to say that HTTPS is secure.
But VPNs aren’t magic. And the safety and security of a VPN depends completely on who owns and runs a VPN and of you trust them. This is regardless of HTTPS being used or not and — sadly but not surprisingly — not all VPNs are run by trustworthy people.
This Lifehacker article from 2013 states it very clearly:
“To a certain extent, you're right. You do have to trust that your VPN service provider has your best interests at heart, because you're relying on them to secure your connection, keep everything encrypted, and to protect your activity from prying eyes. You're connected to their network and their servers, and you have to trust that when they say your exit IP is in Sweden, for example, it really is and they're not just obfuscating something else. It's true—when you sign up for a VPN, you put a lot of trust in the company you sign up with.”
So what does this all mean to you when you are stating basic trust in things like credit card information and such and know that HTTPS will protect you. Easy:
What does the VPN provider log and who might the VPN company share that information with.
For example, you briefly mention government restrictions, right? What if you use a VPN to go to sites your country’s government doesn’t want you to go to via a VPN.
Your VPN provider won’t know any credentials or credit card information you pass along. But if they log your access to a site the government doesn’t like and — if push comes to shove — the government requests data on you from that VPN provider, you could be at risk of the government seeing that you (via your paid account) went to that site they don’t like and can use that as an excuse to harass you, arrest you or even worse.
So before you commit to using a specific VPN provider, do some basic research on them online to see if you trust them. Without naming names a few of the major discount VPN providers have sketchy investors/leadership and some even have a history with malware that they claim they denounce nowadays… But I personally would not trust a place that “cleaned up their act” that way.