The new evolutions are the dark-type Pokémon Umbreon and the psychic-type Pokémon Espeon. As with Jolteon, Flareon, and Vaporeon in the first generation of the game, you can control their evolution by renaming your Eevee before it evolves.
If you want Umbreon, then you should rename your Eevee to Tamao. For Espeon, you should rename it Sakura.
Receiving reports that this Eeveelution name trick has been working, travelers! pic.twitter.com/pwGUIMh4g5
— The Silph Road (@TheSilphRoad) February 16, 2017
The new Pokémon Go update is still rolling out, so remember: This won’t work unless your app has updated to include the new generation of Pokémon!