The game is 12+ rated, but the audience of Embers Adrift is in great majority 30-70 in age. I know there a few parents playing with their children (teenagers) but this is pretty exceptional. Whilst the game certainly can be played by a younger audience, it's most likely not going to attract them.
As for the chat, it is most of the time mature and respectful. But it is also clearly an adult chat. When there is players going out of line, it is moderated.
I would not recommand this game for children younger than 12 years old. And the community is a little older than your usual MMORPG