As Jenipar says. Your country has an arrangement that you can arrive at an airport in the other country & be assessed for a visa then. This usually means that if you are refused a visa then, you have to get back on another plane & go home, without the right to appeal in any way. This is normally only available for pairs of countries where the number of refusals is low. As Jenipar says, it means that you do not have to apply for a visa before you leave. Usually, you can apply before leaving if you want to.

You will not receive a Visa until you arrive in the country. In some countries you have to get your Visa in your passport before you leave to travel there.

That you are allowed to arrive