When you run a command with sudo, you must enter the password.
Then if you enter another command with sudo it will not ask you for a password.
This lasts for 15 minutes, it is temporary.
If, within that time, you run another sudo command, the sudo session will be renewed and the 15-minute timer will start counting again.
This means that if you run a sudo command and then, within the next 15 minutes, run another sudo command, you will not need to enter the password again, since the sudo session is still active.
However, if more than 15 minutes have passed since you last ran a sudo command, the sudo session will expire and you will need to enter the password again to run the next sudo command.