The Spaniard will be in contention to make his Gunners debut this weekend against Newcastle United.
"I always want to play," said Luiz. "I always play in the way the coach wants to play.
"It doesn't matter the side, it doesn't matter which position. You guys know I played a lot of positions during my career. I'm always ready for that.
"It's good when you have a squad with a lot of quality players. We have a game every week, you have to be happy with this."
Luiz added: "He's a great player. It was a pleasure for me seeing Pablo doing really well in Brazil. I hope he can help us.
"He did amazing under Jorge Jesus, a coach I know very well, he's my friend and one of the top coaches in the world.
"I speak with Jorge every week, he's really my friend. He told me to welcome him [Mari] in the best way because he is ready to play."