The Manchester City defender has yet to make his debut for the club.
Mangala was bought for around £32 million from Porto this summer but faces a fight to get into the side at centre-back.
Captain Vincent Kompany plays in one centre-back position and is likely to be the ever-present, whilst Martin Demichelis is likely to be the sternest competition for Mangala.
Pellegrini is quoted by Sky Sports, saying: “He can bring a lot. He is a very strong defender, who is very fast.
“He is only 23 so he can still improve a lot, which is what we were looking for.
“We are helping him to settle here in Manchester and after the international break he will be able to play.
“We need the three of them."
From Pellegrini's description it seems as though he wants a very physical back line. Kompany's presence is a huge factor for City keeping their defence solid, and someone equally as physical with just the same kind of intimidating presence.
There is a lot of power in the Manchester City team and Mangala seems to only add to that, and as soon as he finds his feet in the City side he could prove to be very difficult to face up against.
At 23, he is a signing for the long-term as well, and even when the day comes where Kompany has to move on for whatever reason, it ensures that City retain that powerful presence at the back.
But at that age, the player will want as much game time as possible - though he will get his opportunities after the international break, when the fixture list gets that little bit busier.