The character does not perform its normal attack action. Note this include non-attack actions such as: naruto clone summoning, healer's healing etc.
It have no effects on any character that does not attack.
It expires at end of turn, I believe regardless of when it is applied (some status, such as chaos, does not expire at end of the turn it is applied if it is applied after the character had made its standard attack move)
Interestingly, having blind on sage clone does not affect sage naruto's special attack, whereas having the clone sleeped will cause him to spawn another clone instead of attacking.

This does not however, for one reason or another, stop or delay non-prompt skills. I feel it should since it takes the action slot of the normal attack (mind you, I don't really use blind much, only in ninja exam) but whatever...

Oh, thank you:) And can you tell me, what means "Promt skill"?

Romt ? never heard of it unless u wanted to say prompt :D

Prompt skill is a type of mystery that shows in its description. These skills will be used when you press the *on. Skills that do not have prompt will be cast in place of the character's normal attack that turn.

For example, if I use a mystery at the start of turn 2 it will be used before anyone starts attacking normally. If I use a mystery that does not have prompt, then I have to wait until its that character's turn before they will use their mystery.

Oh, thank you for answer

the face ate the first p I think, not sure what happened to the second p...

In any case, if you look at your mysteries (the *ons that you can click), some of them have the word prompt on them, those are the prompt skill.
Prompt skills are used as soon as you hit the *on, immediately after whatever is currently happening is over (so it won't get in middle of a chase chain etc). Note that it CAN be made between a "before first action" ability and the normal attack that constituted that "first action(which is kinda ironic if that action disappears due to a cc effect but that's another topic altogether) The only actions that can come before a casted prompt skill is another prompt skill of a higher order or inititive order is compared first and in ties, initive is taken into consideration(order is the number on your character's head when you set up formation, 1-4 for us players)
This is assuming no lag, note that 2x generate a lot of graphical delays so except for start of round use, will always lag, so this is mostly about 1x speed

On the other hand, non-prompt skill is a "queued" action, it will get used the NEXT time that character would make a standard move and replaces that standard move. So if you use it at the beginning of a round, it will be used, if not interrupted, that round whereas end of round it will be used next round when the character makes its standard move instead. (note middle of round it will depend on if the character have already made its standard move, if it have, then it will go toward next round)
I'm not entirely certain what happens if:
char A make standard move
char A cast non-prompt skill
char B grants char A an extra standard attack (earth main, kurotsuchi etc)
Not sure if A can cast the non-prompt on its "extra standard attack", thou I assume it could (this could have some interesting effects tbh)