pg_dump
DatabasesPackage: postgresql-client
Exports one database as SQL or in archive format, consistently, without stopping the service. It is the logical backup; until a restore has been tried, it is only a file.
What its options do in the lessons
From the same glossary the lessons render under their commands, so the two cannot disagree.
pg_dump --file- The output file, rather than standard output.
pg_dump --format- The dump format.
customis compressed and allows selective restore, which plain SQL does not.