We got this back in our inspection report. What the heck is it and is it a costly repair?

Means is sloping the wrong way... its supposed to slope down away from your house and its sloping uphill. And as we all know water doesn't flow uphill.

It has to be dug up in order to get a correct slope on it.

How costly it is depends on a lot of things we don't know....meaning whats above it....how deep it is ....how long it is....and what the labor rates are and what equuipment is needed to dig it up.

Internal waste pipe or underground?

If that came from a house inspection report it would have to mean that the drain pipe under the kitchen or bathroom sink is sloped the wrong way. Shouldn't be a big deal.

Did the inspector tell you what pipe it was and where it connects to? Back to you, Tom