Each acquisition is different but there are many ways to fund a transaction as long as the numbers from the financial due diligence stack up.
Such sources may include leveraging the assets which you will be acquiring in the new company to raise funding. This is particularly pertinent to trade debtor books but could equally apply to fixed assets in many circumstances.
Traditional bank loans based on projected cash flows and secured upon either the acquiring or purchasing entity are also commonplace in funding transactions.
As a purchaser, your cashflows may be tight due to the cost of acquisition and deal costs. This is why many transactions also rely on an element of vendor funding by way of deferred consideration.
This is where a vendor agrees to take the money form the deal over a prescribed period following a transaction which may typically span a couple of years.