A concealed hand win is where a player wins without declaring any times, so that all the tiles are concealed at the time of the win. If tiles are part of a Kong, then they are considered to be part of a concealed hand. This achievement is for 100 concealed wins.
When your finishing hand includes a triplet of the Player's Wind, then this will earn an extra point and is considered a Player Wind Win. Collect 100 of these wins to achieve this award.
When your finishing hand includes a triplet of the prevailing Round Wind, then this will earn an extra point and is considered a Round Wind Win. Collect 100 of these wins to achieve this award.
When you have the highest score for the entire round, then that is considered a round win. Collect 1000 of these wins and you will have attained the 1000 Round win achievement.