The Turks and Caicos and The Bahamas are low lying islands, basically sand bars and coral reefs. Category 3, 4, or 5 hurricanes can cause serious damage to these islands. This storm is looking potentially disastrous for these islands, and possibly for somewhere on the east coast of the U.S. if and when it makes landfall there (the models have brought it further and further east as the days have passed but they seem to be in agreement now).
Puerto Rico was was much harder hit than the Virgin Islands, which are not far away at all:
Hopefully those in the path are ready.