You can try cleaning the keyboard using the instructions in this Apple article, but make sure to hold the can of compressed air completely upright or you risk causing damage to the laptop with the cold wet propellant:
https://support.apple.com/en-us/HT205662
If your laptop is covered by AppleCare+, then have Apple or an Apple Authorized Service Provider examine the laptop to provide you with a repair estimate. If the laptop is not covered by AppleCare+, then the laptop may be covered by the free Keyboard repair program:
https://support.apple.com/keyboard-service-program-for-mac-notebooks
FYI, here is the current list of publicly acknowledged free repair programs for various Apple products (some products have multiple programs):
https://support.apple.com/service-programs