Ocean waves with a crest to crest distance of $10$ meters can be described by the wave function $$y=(0.8\text{ meters})\sin[0.628(x-vt)]$$ where $v=1.2 \text{ meters/s}$.
a) Sketch $y$ at $t=0$.
b) Sketch $y$ at 2 seconds.
I believe this to have been in some way derived from the equation $y = A \sin (\omega t + kx)$ where 0.8 is the amplitude of the wave.
I don't understand what the $x$ in this questions comes from. Any clues?
$x$ is horizontal distance in the direction the wave is traveling. $y$ is vertical displacement of the surface. At a given $t$ you now have an equation $y=f(x)$ which you are being asked to graph. You are correct that it will be a sine wave of amplitude ($0$ to peak) $0.8$ meters. The change in $t$ will offset the origin of the sine wave.