I have a Bountiful Harvest. It's a Sorcery that reads "You gain l life for each land you control."
Does this refer to only cards that say Land and not Basic Land, or does it count for both?
A Basic Land is still a land. Any card with "Land" in the type line is a land.
205.1. The type line is printed directly below the illustration. It contains the card's card type(s). It also contains the card's subtype(s) and supertype(s), if applicable.
205.2a The card types are artifact, creature, enchantment, instant, land, plane, planeswalker, sorcery, tribal, and vanguard. See section 3,"Card Types."
305.5. Land subtypes are always a single word and are listed after a long dash. Land subtypes are also called land types. Lands may have multiple subtypes. See rule 205.3i for the complete list of land types.
Example: "Basic Land — Mountain"means the card is a land with the subtype Mountain.
Land is short for land permanent, which means permanent that has "land" as one of its types.
So, if you have a three Forests and one Golgari Guildgate, you'll gain four life.