My Mac Book Air is typing extra/ different letters than the ones I'm typing

H0tAiRmac

Prominent
May 17, 2017
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510
This is almost Impossible to explain since the text/words I type are being changed as soon as I type them. This is extremely frustrating and a huge waste of time. I have tried slowing down the repeat key, but it isn't helping. I turned off the repeat key, that didn't help either. I am using a Mac Book Air.
Please please help.
Thank you.