Raymond,
Thank you for your question! The "Exam" is the requirement for the "Certification." After you take, and pass, the Azure Fundamentals Exam, you will earn that certification.
You can review the exam duration requirements here: https://learn.microsoft.com/en-us/certifications/exam-duration-question-types
For AZ-900, you should expect anywhere from 40-60 questions, and you will have 45 minutes from the start of the actual exam portion.
As for the question about the Voucher, that'd be best to consult with the vendor providing the voucher. Most of the time, courses will include only one voucher unless specified otherwise, but you can always reach out and get a definitive answer from the company.
Let me know if this answered your questions.
Thank you,
Joseph