Duty-free alcohol allowances are set by each country, but the shape is similar everywhere: a fixed quantity per adult traveler, usually split by category, something like a liter or two of spirits, a few bottles of wine, and a modest amount of beer, with spirits treated most strictly. The exact figures vary enough that you should check the destination's customs website rather than rely on airport shop staff.
Where you fly from can matter in specific systems. Travel within customs unions, such as between EU countries, often has generous or effectively unlimited personal-use allowances, while arrivals from outside get the standard duty-free limits. A few countries also vary allowances by length of absence or residency status, and dry or heavily restricted jurisdictions ban alcohol imports regardless of quantity.
Remember the allowance is per qualifying adult, cannot usually be pooled creatively, and applies to everything you carry, including what was bought on the plane. When over the limit, declare and pay; concealment is what converts duty into fines.