Raise both sides as powers of e: e^(x/2)=4y, so y=e^(x/2)/4. When x=0, y=1/4, so the y intercept is 1/4.
When y=0, x is undefined and would have to approach -(infinity). y=0 is the x axis, so the curve can never touch or cross the x axis, making the x axis an asymptote. This means that as x becomes more and more negative, the curve gets closer and closer to the x axis, but never meets it. The curve crosses the y axis at y=1/4.