A checkpoint refers to the location or point in gameplay where a game character respawns after he dies. Respawn is a term in video gameplay that refers to the character coming back to life after it dies or loses all its remaining lives.
Back when technology had not advanced, the point of checks was not typical. Gamers had to let their console stay on until they completed the entire gameplay. If not, the players would have to start the game all over again. But the video games back then were simple, minimal, and had short gameplay, so it wasn't a huge problem.
However, technology advanced, and the size of the games increased. There needed to be a way to store gameplays without having to play all over again. That is when the player's avatar dies in the game.
Most video games have an auto-save feature that does not require the player's assistance. The purpose of the auto-save is to limit the player's frustration from playing the game all over again.
But there are also games which will take the player to a savepoint usually when there's a big action event ahead. A savepoint is a place where the player can save the progress of the gameplay manually. It is generally indicated by a totem, glowing zone, or a terminal.
Most games, especially video games on consoles, don't permit the player to save manually. Instead, the game has selected places where the point of checks are possible. It's not bad video game design, if the developers design it well. If a game designer puts the point of checks or savepoint far away from each other, it can lead to frustration in gameplay. The worse part is when there's no point in checks before a difficult part. They are called a bad point of checks.
Bad checkpoint tells the player to replay most of the gameplay due to their avatar dying or mission failure. But according to game designers, creating a point of checks is not a simple as it sounds. They are both technical and creative problems, and implementing them requires a budget, time, and effort.
During a checkpoint, players can replenish their energy, heal, get an extra life, etc. depending on the game. When the developers do it well, the players can play the game without realizing any point of checks. When the developers don't do it properly, it can lead to frustration, and eventually, the players will leave the game for another.