Pure Inventory voucher perform the same function in the inventory system as accounting vouchers in the accounting system, i.e. they too, are means of entering transactions. In this case, the vouchers record the receipt and issue of goods/stock, the transfer of stock between locations and physical stock adjustments.
If you have chosen not to integrate accounts with inventory, inventory vouchers will not have any impact on the Balance Sheet stock figures. They will maintain the stock balances. However, you can configure Tally so that the inventory entries would automatically update the Balance Sheet stock figures. (By choosing to integrate Accounts and Inventory in F11 Company Features). Remember, you can trace an entire transaction right from the goods transfer stage to the financial accounting of it, irrespective of integration status. For example, the purchase of stock can be tracked form the purchase voucher through to the receipt note, through to the invoice from the supplier and on through to the eventual payment.