If it’s one constant speed, why are we accelerating.

It takes a force to either change speed, or change direction. That force causes an acceleration. So even if the speed is the same, there is an acceleration. We call speed + direction "velocity" so any change in velocity (whether the speed, or direction, or both) counts as acceleration.

pseudo forces

I don’t know anything about this.

There are real forces, like friction, gravity, magnetism, tension, pushes and pulls; and then there are pseudo forces. For example, when you are in a car travelling at high speed, and you turn left, you will feel a force pushing you to the right. This is a pseudo force, because it's not real. There is a real force on the car, pushing it to the left (the friction on the tires). The force pushes the car to the left. But people and objects inside the car want to keep travelling in a straight line. So from their perspective, it feels like something is pushing them towards the right side of the car. But that's just an illusion -- its actually that the car is moving to the left while they are moving forward.

Good demonstrations of why centripetal forces are real but centrifugal forces are fictitious or pseudo forces:

• https://www.youtube.com/watch?v=yAfg_8OLjvs
• https://www.youtube.com/watch?v=ID0R43My4Co
• https://www.youtube.com/watch?v=zHpAifN_2Sw