Stevens signed for Brentford B as a 17-year-old and has progressed through the club’s system as he earnt a promotion to the first team in 2022.
He made nine appearances for manager Thomas Frank's side including one in the Premier League.
Giles has spoken about the 21 year old and how his move to Germany could be perfect for him.
“I love when players come from fairly far down the pyramid, step up and progress and make an impact,” said Giles.
“It was looking difficult for him to get in our team, but to move on to the Bundesliga is just a great story, especially in terms of evolving our B team and developing players.
“It’s important to be able to move players on and bring a little bit of income to the club and show some progression.
“Ryan Trevitt is a similar example: non-league, B team and now he’s involved with the first team. It’s a fantastic story.
“Everyone loves the big signing and the money and all the rest of it, but those are the ones that give me most pleasure.”
St. Pauli Director of Sport, Andreas Bornemann spoke on the move and how it will benefit both parties.
"The acquisition of Fin Stevens gives us more depth in the full-back positions and is partly a response to the squeeze we experienced there towards the end of last season. Fin can influence the game at both ends with his dynamism and goes about his work with great determination and maturity for a young player."
St. Pauli Head Coach, Alexander Blessin also spoke on the move and where the youngster will fit into his side.
"Fin prefers to play on the right-hand side but can also be deployed on the left. He's a full-back who likes to drive forward and get into deep positions. He anticipates well and is brave and aggressive in the tackle, switching the play quickly after winning the ball."