Why is my laptop typing on its own?

I presume you have already vacuumed the keyboard with a crevice tool to get rid of junk that occasionally cause sticky keys.
Next, close the top and turn it upside down. You will see 4–6 screws small that have a “K” (for keyboard) next to them. Tighten those screws. As you look at the bottom, I’m guessing the ones in the upper left are loose.

I have done the vacuuming but not all the rest. Thanks, I will try.

While you have it upside down you might as well tighten everything. Let us know how you make out.

Another thing is that some laptops and computers come with a form of speech recognition. You may have accidentally turned it on and it’s capturing your talking or other sounds. This happened to me several times before I figured it out. If the maintenance suggestion doesn’t work, look to see if your speech recognition is on.

It doesn’t have speech recognition.

Is it a laptop with a removable battery? My 2007 MacBook (not Pro), had a removable battery, and someone seuggested I change it, after having the same problem. It worked! I guess batteries “swell” sometimes? Considering, at the time of changing it, it was presumably a couple of years old; I can’t remember how long ago it was, but I’d venture a guess and say it was at least 3 years into having the machine. Saved me from replacing the laptop for the time-being, and it still works.

Yes it has a removable battery. I never have the battery attached though!