Reimbursement, as the dictionary mentions, is a compensation paid for money already spent. Depending on your policy, reimbursement claims mean you pay the bills first and get them compensated from the company later on

Example:
For example, if you had to rush to hospital for some tests, you can pay the money initially and file a reimbursement claim with your health insurance company by attaching the necessary documents. Once verified, you will be reimbursed the money in your registered bank account.