Hi @LAILA.TAIK ,
per vote the author of the question/answer/comment/feedback gets 5 Reputation points: https://learn.microsoft.com/en-us/answers/support/reputation-points#how-to-earn-reputation-points
As far as I know there are not limits for the votes of questions/answers/comments.
The usefulness of votes is to show a question/answer/feedback/comment is good/helpful. This is in addition of "marked as answer" answer which can only done by the person who asked the question. Everyone who will find the question/answer/comment helpful can vote for it.
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(If the reply was helpful please don't forget to upvote and/or accept as answer, thank you)
Regards
Andreas Baumgarten