If you hit s does it also type out sx or xs? if so it sound like a problem in the physical switch of the key.
Also bring up the onscreen keyboard,
https/www.isunshare.com/windows-10/6-ways-to-turn-on-on-screen-keyboard-in-windows-10.html ,and make sure there isn't some weird macro doing it. If it work then its decently an issue with the driver or physical keyboard. Also try and use an external keyboard and see if that works ok.
For the driver uninstall it via the Device Manager manager and reboot the laptop, Windows should be able to find an appropriate driver, if for whatever reason it can't then you'll need to look on the manufacturers website, might be handy to have it downloaded and ready to go just in case.
If it's something with the physical keyboard you can try and carefully pop off the offending keys and clean out and around the switch with a soft cloth and some rubbing alcohol while the computer is off and battery disconnected if possible.