Pokémon Sword and Shield/Route 3

Before you're able to head into Route 3, Hop will be waiting for you, so you'll have to battle him to be able to continue.

Rival: Hop
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🇨🇴 🇨🇴

After you defeat Hop, he'll hand you one of his League Cards, and you'll be able to head onto Route 3.

Route 3
As you head through the route, you'll meet with Sonia, who will tell you about a building owned by Chairman Rose's company, which transforms ore into energy. She'll comment on Rose's brilliance, and will then hand you the Escape Rope, which is now a Key Item which is reusable, for talking with her.

After you've talked to Sonia, keep heading through the route, always proceeding west, until you end up reaching the entrance to Galar Mine. Before doing so, however, you're free to go around collecting items and building up your team if you think it's necessary.