There are several things you can try, to narrow down whether the problem is with your keyboard hardware or with something related to Windows.

Connect an external USB keyboard and try that for a while. If the issue also occurs with the external keyboard, then the issue is something in Windows. If the issue does not occur with the external keyboard, then it's likely a hardware issue with the onboard keyboard and it may need to be replaced.

Here are some other things to try:

• Try a power reset (unplug AC adapter, disconnect battery, hold down power button for 30 seconds to discharge flea power. Then connect the AC adapter and try it).
• Go into Device Manager and delete the keyboard driver. Windows will install the latest.
• Use the keyboard troubleshooter. Troubleshoot settings | Additional troubleshooters | Keyboard
• Try in Safe Mode to see if the issue occurs there.
• Try the Windows on-screen keyboard. If on-screen keyboard also exhibits the issue, it could be due to corrupted system files. Run SFC (System File Checker) scan on your PC to repair those files.
• Try in Linux (by booting from a flash drive with Live USB install of Ubuntu, Xubuntu or other) to see if occurs there, outside Windows.

Dell keyboard troubleshooting guide:
https://www.dell.com/support/kbdoc/en-ca/000131432/keyboard-usage-and-troubleshooting-guide