A pull creates a ball that starts and stays left of the target. Either one is not good, as they do not end up at the target. A slice has more spin than a pull, so it travels less distance.
To correct either, it is imperative to identify the root cause. The clubface is the first place to look. With a slice, the face is open to the path at impact. With a pull, the face is square to the path, just too far left. If it hooks the face is closed in relation to the club’s path.