How does direct path load work when dataguard is enabled?
If the database is setup correct: no direct path load. If a standby database is depending on the changes captured on the primary database, the primary database should be setup with force logging.

If for some reason the force logging setting is not in place, after such an operation the affected datafiles should be transferred to the standby site[s]. Failing to do so will make queries on the loaded parts of the table[s] in the standby database to fail.