Assumably you saw the bonus tile icons. Some tiles have special features on them which will provide a bonus if the correct type of improvement is built there. For example, you may come across a tile with rare mineral deposits; if you build a factory on that tile, its output could be doubled (or more). The bonuses are non-transferrable and only apply to a particular type of value (so if you build the wrong sort of improvement there, there will be no bonus).

sure, the link is http://images.stardock.com/ss/shotstore/19/The%20Universe/new-6.JPG

as you can see theres a little pink leaf thing there, "trade good"

thanks for answering my question!

Actually, trade (especially between civs) is more critical in GC II than in most other RTS games, and is often the key to a culture victory (in fact, I couldn't have won my first game without it). One thing I made sure NOT to neglect, especially in the early game, is manufacturing, farming, and research bonuses on new colony worlds; the result had me become the *go-to civ* for food crops and basic manufactured goods (unusual for the Yor, who I play as) devoting just as much to research as I did to farming or manufacturing (unless I have more research bonus squares than farm/manufacturing bonus squares) let me maximize the Yor's already healthy research advantages into market cornering in heavily-in-demand NON-military trade goods (not only letting me develop a huge trade surplus, but letting me actually *expand* said surplus with few economic starbases).