Answer 1

a parameter is a sort of argument that helps to declare new variables
for that function.
eg int carspeed (int speed1){
return speed1;
}
in the above example, int speed1 is a parameter of the carspeed function. In other words, speed1 is a variable of the carspeed function. Its just like declaring a new local variable inside a function. e.g
int carspeed (){
int speed1;
return speed1;
}
But the difference between declaring a variable as a parameter and declaring it as a local variable is that if you declare it as a parameter, you can easily input the value of speed1 in another function by simply calling the carspeed function like this

int main (){
carspeed (15);

return 0;
}

hope this helps.