Question 721854
(1)  It's a function. You can call it f(x), or 
a function of x.
That means that there is 1 and only 1 value of f(x)
for each value of x.
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If there were 2 possible values of f(x) for a certain x,
then it would be disqualified as a function.
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(2) It's a 2nd degree equation, also called a parabola
Here's the plot:
{{{ graph( 400, 400, -5, 5, -16, 5, x^2 + x - 12 ) }}}
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You can see that there are 2 x-crossings, called roots. That is a feature
of 2nd degree equations- 2 real roots. If there were no
x-crossings at all, then there would still be 2 roots,
but they would be imaginary. 
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Hope this helps