Seki (meaning “mutual life” in Japanese) is an uncommon occurrence in Go where a group can be living when it doesn’t have 2 eyes.
On the right, both the black and white triangled groups are alive because they cannot approach each other.
If black plays first, black reduces their own group to 1 liberty. White’s turn is next and white will take the group.
If white plays first, white reduces their own group to 1 liberty and black will take them next turn.
Because neither player can approach first, both of the groups are alive and the area in between them is dame ( dah-meh, i.e. noone’s points).