What is a staggered conformer in a Newman projection?
A staggered conformer in a Newman projection is one in which the bonds from the rear carbon bisect the angles of the bonds in the front carbon.
For example, the staggered conformation of ethane is
The torsion angle — the angle between
This puts the atoms on the rear carbon at the maximum distance from those in the front.
It also minimizes the van der Waals repulsions between groups.
Here’s a video that shows the conformations of ethane and their energies.