Mane and Wijnaldum both signed long-term deals at Anfield, becoming Jurgen Klopp's latest additions to his squad ahead of the 2016-2017 Premier League season.
Coutinho is excited by what both players bring to the team, especially their injection of pace.
"I am looking forward to playing with them. They’re both very good players and fast players, so maybe you can pass a long ball and they'll arrive to it," the Brazil international told Liverpool's official website.
"But it's not only them, the squad is very good and there are a lot of good players. I hope we can all do a good job together this year.
"There are a lot of players now and there is good competition in the squad, which helps you to get better and helps the team.
"It's been very good playing with Sadio so far, but if anything he’s too fast! That's good because you need this in your game. Everyone is very happy with him – he is a nice guy and very good player.
"The new signings are] very good for Liverpool and the squad because there is good competition to play. Everybody wants to be involved and that’s good for the club."
Coutinho, who arrived at Anfield in January 2013 along with Daniel Sturridge, is one of the longest-serving players in the Liverpool squad after Martin Skrtel's departure to Turkey.
Only compatriot Lucas Leiva, captain Jordan Henderson and Joe Allen, who is reportedly set to join Stoke City, have been around longer.
'I feel young!" the 24-year-old Coutinho said with a smile. "I always try to be myself, I don't think I am an experienced player because I am always trying to learn from every player and every coach in the squad.
"The time has passed very quickly since I moved to Liverpool and I am very happy because this is a great club. Now we have some new players and let’s see what happens this season."