Seems like a bad drive, or faulty enclosure, cable, or adapter.
Try connecting the drive to another USB-C port especially on the other side if using a laptop.
Has this drive (cable & adapter if used) worked on this laptop previously? If not, then perhaps this external drive just is not compatible with this Mac. The JMicron USB chipset is one which I know has had some compatibility issues in the past...I consider a low end chipset used on inexpensive USB devices.
You can try disconnecting all other external devices in case one of them is causing a problem.
Make sure to connect the drive directly to the computer since docks, hubs, adapters can sometimes cause problems as well. If you have done this, then perhaps try connecting the drive to a powered USB3 hub in case the drive requires more power than the computer can provide.
You can also try booting into Safe Mode to see if that makes any difference.
You can try checking the health of the external drive by running the third party app DriveDx (free trial period) and posting the complete text report here using the "Additional Text" icon which looks like a piece of paper on the forum editing toolbar so we can examine it for possible clues. You will need to install a special USB driver in order to attempt to access the external drive's health information. However, even with the special USB driver, some adapters/docks/enclosures may prevent access to the drive's health information.
Try connecting the drive to another computer to see how it works.
What is the exact model of your Mac and version of macOS? You can get this information by clicking the Apple menu and selecting "About This Mac". FYI, this information should always be provided when asking for assistance online since it is almost always needed.
Also, what is the exact make & model of the external drive? What file system is on the external drive?
