Professor Birch runs the Pokémon Lab in littleroot Town. As part of the story, you'll find him under attack by wild Pokemon. When you save Professor Birch, you will have your first meeting with the Pokémon that will become your partner on your journey, and a new bond will be born. Birch has been good friends with your father, Norman, since their school days. He has a tendency to get enthralled with Pokémon and leave home for long periods.
After saving him, you'll get the starter you used to save him earlier and a Pokedex. This simple event triggers your journey to become a Pokemon Master!