Diagon Alley-
Diagon Alley is a cobbled wizarding alley and shopping area located in London, behind a pub called the Leaky Cauldron. Inside the alley is an assortment of restaurants and shops. All items on the Hogwarts supply list can be bought at Diagon Alley, which is completely hidden from the Muggle world. It is very large in area and essentially the centre of wizarding London.
Chocolate Frog-
Chocolate Frogs are a popular confection that are sold throughout the wizarding world. They are packaged with collectible cards portraying famous wizards and witches. Many of the pupils at Hogwarts collect and trade these cards.
Floo powder-
Floo powder is a glittery, silver powder used by witches and wizards to travel through the Floo Network. The Network connects most wizarding households and buildings. The powder turns a fireplace's flames harmless and emerald green. It is tricky to use; one must toss a handful of powder into a fireplace connected to the Floo Network, walk into the flames, and state the desired destination loudly and clearly to ensure arrival in the proper location.
Golden Snitch-
The Golden Snitch is a ball used in Quidditch. It is a small gold-coloured sphere with silver wings and is about the size of a walnut. It flies around the Quidditch field at high speeds, sometimes pausing and hovering in place. The Seeker's goal is to catch the Snitch before the other team's seeker, which is worth one-hundred and fifty points. The game can only end when the Snitch has been caught, or by mutual agreement of the two teams' Captains; the latter is very rare, however, as one team would have to lose.
Hanged Man-
The Hanged Man was a pub in the Muggle part of Little Hangleton, a village in England.
Incendio-
Incendio is a fire-making spell (unlike the first answerer said, it's not a fixing spell).
Mudblood-
Mudblood is a derogatory term for a Muggle-born wizard or witch; that is, individuals with no wizarding parents or grandparents .