It means careful picking out the stitches but it is relatively easy to replace at this point if you really want to. You can certainly hand sew in the replacement, whether over the top as an applique or as a replacement. I would go by machine.
Basically think of it as a partial seam type of thing. There are videos and tutorials -- I caught an episode on one of the sewing shows this weekend/ Take out a bit of the row and column seams around it, just half an inch or so. Carefully place the one "short" side and sew it, then the opposing side, then the "long" sides.
LOL, the hardest point is when it is already quilted and even then -- many of use have felt the need to completely fix something.
Take deep breaths, and persevere. I call taking out sewing "frog" stitching -- rippit! rippit! (being very careful not to rip...)