Does that mean I wrote something in my code wrong (grammatically) that has to do with the particular function?
Yes. Look up how to use a digitalWrite function:-
Now do you actually want a digital write here. It does not return a value so it is odd that you have it on the right of an equals sign.
buttonState1 = digitalWrite (buttonPin1);
Should in fact be:-
buttonState1 = digitalRead (buttonPin1);