Firefox typing feature: Whenever I type my first letter, it is capital, and whenever I add an comma to my sentence and hit the space key, it adds an period.

Hello, Firefox. So I have this feature whenever I type. When I type my first letter, it is capital, and whenever I add an comma to my sentence and hit the space key, it adds an period. I don't remember enabling that feature, and I want to disable that feature. Is there any way if I can disable that feature? Thanks in advance!