Please explain the passage, "Unreal city...weekend at the Metropole" from T.S. Eliot's The Waste Land.

This passage comes in the third section of Eliot's "The Waste Land," which he entitled "The Fire Sermon".  In this passage, Eliot is referring to being in a city (to which he also referred to in the first section of the poem, and indicated that it was in London), and being approached by a man.  This man, "Mr. Eugenides," who is a merchant from the Turkish port of Smyrna, asks Eliot if he would like to go with him to a hotel and have lunch, followed by spending the weekend with him.  The hotel listed, the Cannon Street Hotel, was at the time known for people who wanted to meet in secret, without being known.  The allusion here is that Mr. Eugenides is a homosexual, asking Eliot to go to lunch and spend the weekend with him, in a sort of tryst.

The other references in this passage simply refer to the fact that it appears that Mr. Eugenides has freshly arrived in London and still has his passport, documents and other travel items with him.  "C.i.f. London" refers to a ticket stamp that meant "carriage and insurance free."  The man also spoke vulgar ("demotic") French.

This passages goes along with the theme that Eliot has addressed in his poem of people who have no love in their lives, and so use sex and other sensory fill-ins as substitutes.  He describes lonely, miserable people who are trying to fill the voids in their lives; this man who approaches him is just another one of those people seeking happiness in temporary relationships.

I hope that helps a bit; good luck!