If a country in your itinerary requires a visa, you’ll usually need to present it at the airport during check-in, security, or immigration. You won’t need to provide visa details when you check in online, but it’s possible you might still need to go to the check-in desk at the airport and provide it.
Some airlines issue a “placeholder” boarding pass and provide a real boarding pass after checking your visa. If that’s the case, you’ll see this info stated directly in the placeholder document.
For more on visas, read this.
For the latest travel requirements we recommended checking our partner Sherpa's website, or the official government websites for all countries in your itinerary before traveling.