If it is the new MacBook Pro butterfly keyboard, the dust may stuck inside your number 0 key. You'll need to clean it using a canned air. You need to follow the steps here: https://support.apple.com/en-us/HT205662.
Otherwise, if other keys are not working, you'll need to replace the whole keyboard for free on Apple Store or Apple Authorized Service Provider for four years of purchase. You need to visit this site here: https://support.apple.com/en-ph/keyboard-service-program-for-mac-notebooks.
If your MacBook Pro model is 2015 or earlier, you need to service it at Apple Store or AASP. In the meantime, you can use the external keyboard for your purpose.