In the literal sense, it's a pyramiding method of taxation that assesses tax on the amount of value added to items in each stage of production until it reaches the end user. You're saying something like, "I'd rather dry fuck a bag of razors than pay an income tax until somebody can explain the income part of it," when income taxes tax income.
In the abstract sense, it's a tax that generates considerable income (due to the breadth of its scope) while incentivizing tax compliance instead of avoidance for sellers. It's good value for (government) money, assuming that taxpayers actually take the incentive to be compliant. (Despite what economists wishfully think, taxpayers do avoid tax for no logical reason.)