What is the vertical asymptote of y=1/(x+3) ?

The vertical asymptote of $y = \frac{1}{x + 3}$ will occur when the denominator is equal to 0. In this case, that will occur at -3, so the vertical asymptote occurs at $x = - 3$. There is no y-coordinate to be included.
For a more thorough explanation behind vertical asymptotes, see here: http://socratic.org/questions/what-is-a-vertical-asymptote-in-calculus? In summary however, vertical asymptotes occur at $x$-values where the limit of the function, either overall or from the right or the left, approaches $\pm \infty$.