For clarification, exactly what are you booting in? Is it a flavor of Ubuntu? Is it Windows?
Anyway, notice how on the bottom left of the provided screenshot it says "err". That means something went wrong (error). I recommend making a bootable USB again using whatever software you have access to. After that, restart the system. While it is still booting up, use this link as a key to find what button to press to gain access to BIOS. Head over to the boot tab using arrow keys. You should see a list of boot options, with your USB as one of them. Select it by pressing enter while hovering over it and move it to first spot.
Digestible List:
- Create a new bootable USB either using dual-boot or separate computer.
- Restart your system.
- Find your BIOS button from the link above and use the arrow keys to find the boot tab.
- Select your USB and prioritize it in first position.
Sometimes, you can't see the USB stick in BIOS. If that is the case, go into your Boot Options (it varies but is most commonly F12) while it is still booting in, and you should see the USB there. If not, you did something wrong and further help is needed.
Digestible List:
- Restart your system.
- Press F12, a quick Google search can help you find your key to press.
- Press enter after using the arrow keys to select your bootable USB.