The Rotate operation allows rotating the scene around the current pivot axis, or tilting the scene on an axis that parallels the view window plane, by moving the mouse with the left button down.
The Move
operation allows moving the scene up and down the pivot axis and along
the same axis as is used by Rotate by moving the mouse with the right
button down.*
To lock along one dimension or the other, hold either of the 'V' or
'H' keys down while moving the mouse around.
For Rotate operations, the 'V'
modifier enables tilting but disables rotating around the pivot axis;
the 'H' modifier disables tilting but enables rotation.
For Move operations, the 'V' modifier enables moving up and down the pivot axis, but disables moving back and forth; the 'H' modifier disables moving up and down the pivot axis, but enables moving back and forth.
Shortcut to toggle on/off the picot axis display: Ctrl+Shift+P
*Note that Move Mode allows the same operations but reverses the mouse
buttons that trigger them.