O "
é escapado com uma barra invertida porque '"
está entre aspas duplas.
:help '"
diz:
To the cursor position when last exiting the current
buffer. Defaults to the first character of the first
line. See last-position-jump for how to use this
for each opened file.
Only one position is remembered per buffer, not one
for each window. As long as the buffer is visible in
a window the position won't be changed.