What do these terms mean?
HF = Harbor Freight, a national chain that sells mostly tools and related items.
HFGH = Harbor Freight GreenHouse. Harbor Freight carries two inexpensive greenhouses. The 6x8 foot model usually runs about $329 and the newer 10x12 foot usually runs about $699. Both are metal frame structures enclosed with twinwall polycarbonate panels.
And they're both on sale right now ($299 and $599 respectively). Check on the harbor freight web site and search using "greenhouse".