what does phase really mean?
You misunderstand the question.
They are asking - "If you move the waveform along the axis so that it's maximum amplitude is at 0 degrees, how many degrees do you need to (phase) shift it?".   

Draw some pictures.
A "normal sine wave" starts at V=0 at time = 0 - so it certainly isn't at maximum value at time 0, as you suggest.   

Now (phase) shift the wave until the peak is at 0 degrees.
How many degrees did you have to move it?