Coutinho joined Barcelona from Liverpool in January 2018, following a five-year stay at Anfield where he etched his name as one of the best players in the Premier League.
The former Inter Milan man failed to live up to his standard after two seasons in Spain which led to him been loaned out to Bayern Munich ahead of the 2019/2020 season.
Coutinho ended his loan spell with the Bavarian giants winning the treble.
His future in Catalonia was previously in the air but new head coach Ronald Koeman has given the 28-year-old the second chance to prove himself at Camp Nou.
“I'm having a very good time," Coutinho, who has started all three La Liga games so far, told reporters while on international duty with Brazil.
"In these seasons I have achieved many things on a personal and collective level, which is the most important thing.
"I have returned to Spain with a lot of desire for things to go well and it is also what I want in the national team, every opportunity I have I want to play great games giving my best for the team."
“At Bayern, I learned a lot about work, because they are very intense in training," he added.
“A natural consequence is the evolution in the physical part, which I have really had, because you work a lot and I have worked a lot.
"I already had this way of thinking, but now I have to dedicate myself three or four times more than normal to be successful."
