If a object is moving in circular direction and has a constant speed, is the object keeping a constant acceleration.

No.

The magnitude of the acceleration will be constant, but the direction of the acceleration will always be changing.

In uniform circular motion (when the object moving in a circle has a constant speed) the acceleration, and the resultant force which causes the acceleration will always be directed towards the centre of the circle. We call this "centripetal" acceleration, which means centre-seeking.

Because acceleration is a vector quantity (meaning it has both magnitude and direction) it's not true to say the acceleration is constant in uniform circular motion, but it is true to say it has constant magnitude.

Yes the magnitude of the acceleration(and centripetal force) will be constant but the direction of acceleration (and centripetal force) is towards the centre. This will be in a different direction depending on where the object is in the circle. So the direction of acceleration will change, and since acceleration is a vector, the acceleration will be changing and so not constant. Same for the centripetal force -that will not be constant as its direction will change.