What are some countries that colonized Africa?

The 7 European powers listed above benefited greatly from the African Colonies, which weren't always positive but without those reaping's from the colonies, much of the modern history & technologies may not have been developed.

The most notable undertaking of using African Colonies was the Slave Trade & the infamous Transatlantic Slave Trade.
In a nutshell, a 'plotted' triangle of which ships would travel down to the west coast of Africa from Europe & trade weapons such as guns to Native African Warlords usually for captured men, women & children from their conquests.

They'd then make the horrific journey across the Atlantic, to the west indies, with the black African slaves packed like sardines in the hull of the ship, sleeping, eating & excreting amongst each other, with only the odd hour or two jumping around on the deck.

They'd finally reach the West Indies (if they hadn't died & been thrown off & fed to the sharks) where they would be sold to Sugar Cane farms as slave labour, usually on islands such as Jamaica.

Once the slaves had been sold, the dangerous journey back across the Atlantic with a boat full of the usual Sugar Cane, would bring the crew & their country of return a lot of money once it was traded.

A sad yet interesting subject, from which cultures from the West Indies sprang from & the beautiful yet bloodily paid & made for buildings & paintings of Europe.

Hope this helps & the extra info.