What does the following quote mean? (Explain)

In context, Eliza believes herself to be acting in the appropriate manner but falls into her old ways of speech. Freddy and his sister, unaware of Eilza's true social position gind her charming and modern.

liza is shown in, exquisitely dressed, and she makes quite an impression. In fact, Freddy falls in love with her. Mr. Higgins realizes that they all met on that day at Covent Garden, but nobody else makes the connection. Eliza, who has been warned to limit her conversation to the weather and to people's health, talks about an aunt of hers who supposedly died of influenza but who was perhaps killed so that the killer might steal her new straw hat. Mr. Higgins grows alarmed, and Eliza leaves, but the Eynsford Hills think that by talking about coarse subjects and swearing, Eliza was using a new, fashionable type of slang. Pickering tries to support this assumption by declaring that he can no longer distinguish high society from a ship's forecastle now that people swear so often. Clara declares the "new slang" charming--and to her mother's horror, she herself uses the British curse word "bloody."