If from the non sim card phone i turn on the vpn, then use a hushed number(burner number) and connect to my other phone which has a sim card and uses cellular network over a mobile hotspot wireless connection on the other phone , is the first phone protected and secure and private so that nobody can access the information i send over it?
Short answer: Sort of, yes. Let me elaborate and clarify. First, a primer on VPNs:
VPN tunnels are between two endpoints. If your VPN is on your burner phone, the other endpoint is usually the provider or VPS. (e.g. VyprVPN, ProtonMail, etc). This creates a tunnel of encrypted traffic between these two, meaning your ISP (and anyone else in the middle, like someone on Wifi) cannot see your traffic. However, this does nothing to protect your other, non-burner phone. The only thing encrypted is packets sent and received on your non-burner phone.
However, if you set up and create a hotspot on non-burner phone, and use this hotspot on your burner phone, then connect VPN on burner phone, your burner phone will still remain anonymous (see bottom for note on this) and encrypted - but traffic orginating from your non-burner phone is not. Meaning anything sent/received from your non-burner phone is still visible, while your burner phone is (relatively) safe.
Or does the data sent through the wireless hotspot connection become visible through the phone which is offering the wireless hotspot connection?
Short version: Your burner phone will remain anonymous, but your non-burner phone will not. As long as the data is only going through the hotspot with a VPN connected, you should be safe. If you want anonymous info on your non-burner phone, set up a VPN on that one, too.
Note on anonymity - VPN's alone are not enough to ensure true anonymity. Things like DNS leaks can compromise your IP, so if you want true anonymity, you will need a layered approach. Perfect anonymity is nearly impossible, however, and requires going through lengths most people will find annoying or even eccentric. I am not addressing those, I'm simply discussing the VPN traffic as you presented the question. VPN's are a huge step in protection, and will make it considerably more difficult to track you, especially for usta casual user - difficult, but not impossible. I thought it important to clarify this distintion.