Saliba has ended his loan spell with St. Etienne, where he returned for a season after the two clubs agreed a permanent move last summer.
"I am discovering another world."
On not being able to play in the Coupe de France final against PSG, Saliba added: "It would have been my first final, my second year as a professional.
"Of course I hope to play other finals, but you are never sure of anything. On top of that, it would have been my last match with the club that formed me. I hoped, hoped. Truly.
"Even when it became impossible. The two clubs did everything for me to play. But they did not reach an agreement. I was very disappointed."
Saliba has been assigned the No.4 shirt when he arrives at Arsenal.