It is a support of payment, given by the company to there employees, to subsidize part of the cost of their employees meals (during the business hours).

It is usually used for a payment in a fast food style restaurant but can also be used in participating supermarkets, bakeries and others.
Restaurant vouchers are considered as an additional revenue exempted from social taxes.
Benefits in cash can often be fully taxable, but not the restaurant Vouchers.For employees it's considered as an additional revenue tax exempt (social taxes).

For employers, there are also consderable cost savings from simplfied administration and employer payroll.
No need to outsource catering, no high running costs of a staff canteen, no complicated expenses claim procedures.
Restaurant vouchers are a tax exempt advantage thet has benefits for all.