Essentially it means oboe of love in Italian. In the double reed family along with the oboe, the english horn, bassoon etc, the oboe d'amore is an unusual but goreous instrument. It has a slightly more tranquil tone and it's bell is shaped like an apple. It is in the key of A whereas oboe is in C and english horn is in F.
After waning popularity in the late 18th century, the oboe d'amore fell into disuse for about 100 years until composers such as Richard Strauss (for example in the Symphonia Domestica where the instrument represents the child), Claude Debussy (for example in Gigues, where the oboe d'amore has a long solo passage), Maurice Ravel, Frederick Delius, and others began using it once again at the end of the 19th century. It can be heard in Toru Takemitsu's "Vers, L'Arc-en-Ciel, Palma," but its most famous modern usage is, perhaps, in "Boléro" by Maurice Ravel where the oboe d'amore follows the E-flat Clarinet to recommence the main theme for the second time around. American composer William Perry uses the oboe d'amore in his film scores and most recently in the third movement of his Jamestown Concerto for Cello and Orchestra (2007).