Two concepts that play into discussions of the NFL draft are positional need and positional value.
Positional Need is a pretty straightforward concept. If you lack players of the needed quality (and that could be starters or backups), then you have a need. If you have a depth chart that is fully loaded at a position, you probably don’t have a need; you may even be in a position to trade players away.
Positional value is less straighforward, but most committed NFL fans have an intuitive grasp of the concept.