In accounting, a provision is an account which records a present liability of an entity. The recording of the liability in the entity's balance sheet is matched to an appropriate expense account in the company's profit and loss.

Providing for bad debts or income taxes payable in the future.

The example you're most likely to come across is providing for a bad or doubtful debt. This is when you're not expecting to recover a portion of the money you have outstanding from a client because they have fallen in to bankruptcy or something like that. When this happens, you will record an expense for the amount in your current period that you think may go bad at some point in the future.

Provisions are a type of Accrual however generally get categorised separately from your accruals because the outcome of what the value will end up being is more of an unknown.