till now I had 5 questions from people te book my place, and thay are sending me a message that thay can not book because thay are not able pay to airbnb, ??? whay is that, their card is ok and thay have mony on it, Could I done something wrong??
You have done nothing wrong - there is a problem with their card. They need to sort it out. Under no circumstances should you agree to accept cash as it may be a scam.
There are lots of very good reasons why AirBnB will decline payment - which protects you against fraud, etc..
Just suggest they contact BNB - contact details are listed in the 1st post Community Help forum.
As already suggested there could be that there isn't enough funds on their card, they could be trying to use a payment method not approved by BNB such as Amex or there could be a technical glitch.
Whatever the reason, only they can sort it out with BNB directly.