Question: how to evolve eevee into umbreon by walking?
Answer: You need to walk 10km and collect 2 candies with the Eevee you want to evolve as your Buddy. The Eevee you want to evolve must be set as your current Buddy during evolution. Evolving the Eevee during the day will turn it into an Espeon. Evolving the Eevee at night will turn it into an Umbreon.