A tax rebate is essentially a refund — the government returns money to you because you overpaid your taxes. This can happen through excess withholding, eligible tax credits, or deductions that reduce your liability below what you already paid.
For example, if your employer withheld $15,000 in taxes throughout the year, but your actual tax liability is only $12,000, you get a $3,000 tax rebate.
Governments also use tax rebates as economic stimulus. During downturns, rebate programs put money back in people's pockets to boost consumer spending and stimulate the economy.