wouldn't be able to see anything

[ssss1]

(Twelve times he clicked the Put - Outer , until the only lights left on the whole street were two tiny pinpricks in the distance , which were the eyes of the cat watching him .)
If anyone looked out of their window now , even beady - eyed Mrs. Dursley , they wouldn't be able to see anything that was happening down on the pavement .

( extracted from Harry Potter and the Sorcerer's Stone by J.K. Rowling.)

Which does this sentence mean "only wizards can see the magic that Dumbledore did" or "if anyone witnessed the magic, they wouldn't be able to believe it is real"?

 

[Tarheel]

Nobody else could see it. Only wizards could.

It would not make sense to them. They wouldn't be able to believe their eyes.

 

[emsr2d2]

(Twelve times he clicked the Put-Outer, until the only lights left on the whole street were two tiny pinpricks in the distance, which were the eyes of the cat watching him.)
If anyone looked out of their window now, even beady-eyed Mrs. Dursley, they wouldn't be able to see anything that was happening down on the pavement.

(Extracted from Harry Potter and the Sorcerer's Stone by J.K. Rowling.)

Which Does this sentence mean "only wizards can see the magic that Dumbledore did" or "if anyone witnessed the magic, they wouldn't be able to believe it is real"?

Note my corrections above. Concentrate on spacing around punctuation:
- Don't put a space before a full stop.
- Don't put a space before a comma.
- Don't put a space after an opening bracket or before a closing bracket.
- Don't use a space on either side of a hyphen.

 

[5jj]

(Twelve times he clicked the Put - Outer , until the only lights left on the whole street were two tiny pinpricks in the distance , which were the eyes of the cat watching him .)
If anyone looked out of their window now , even beady - eyed Mrs. Dursley , they wouldn't be able to see anything that was happening down on the pavement .

If anyone (living in that street), even one with very sharp eyes (like Mrs Dursley) looked out of their window, they would not be able to see anything that was happening on the street. The Put-Outer had extinguished all the lights; it was very dark.