It means the balcony is enclosed, so if you are sitting outside you can’t see the view (unless you stand up) and your view from inside the room is obstructed on the lower half.
For comparison ~
Open balcony:
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Dormer room balcony outside:
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Dormer from inside:
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The rooms at WL are considerably smaller than Poly and Contemporary, but are fine for 3 adults. We enjoy the club level food offerings and the views from above looking down into the lobby are great. The lounge is also much less crowded than other CL lounges, as there are far fewer CL rooms at WL. Staff is warm and friendly.
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There is a deck outside the lounge for fireworks viewing (with soundtrack) should you receive a room that overlooks the pool.