Hogsheads were essentially large barrels of tobacco.
A standardized hogshead measured 48 inches (1,219 mm) long and 30 inches (762 mm) in diameter at the head (at least 550 L/121 imp gal; 145 US gal, depending on the width in the middle). Fully packed with tobacco, it weighed about 1,000 pounds (454 kg).
Barrels were good because the shape would allow them to be rolled then loaded on board merchant ships. An interesting feature of putting tobacco in large barrels / hogsheads was that sometimes unscrupulous dealers would put sub-par tobacco in the middle of the barrel, hoping to hide the poor quality from the inspector. Local tobacco inspectors in New Amsterdam, seeking to protect the reputation of tobacco leaving New Amsterdam, would open the barrels, check the tobacco, and label it according to quality (there were 4 grades); sometimes they would "unhoop" the barrels when they thought there was an effort to conceal the true quality of the hogshead - clearly a deterrent for the merchant with something to hide.
For more information on barrels: