It's hard to tell what data you're even working with, but the standard object name is simply [`Pricebook2`][pb2] (_no underscores_).

If you are trying to insert a record looking up to this object (_such as [`PricebookEntry`][pbe]_), the name of the lookup field is `Pricebook2Id`.

[pb2]: https://developer.salesforce.com/docs/atlas.en-us.api.meta/api/sforce_api_objects_pricebook2.htm
[pbe]: https://developer.salesforce.com/docs/atlas.en-us.api.meta/api/sforce_api_objects_pricebookentry.htm