Protego!
Protego is the shield charm, a spell that creates an energy barrier which deflects minor to moderate hexes as well as physical objects. It will not repell any Unforgivable Curse. The Shield Charm is a moderately difficult spell. Fred and George Weasley realized that most adult wizards, even those employed by the Ministry of Magic, could not produce a functional Shield Charm. They used this to their advantage when marketing their line of protective clothing (hats, cloaks, etc), upon which Shield Charms were cast.
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Impervius. it repels water :-)
It is unclear in the book, however, in the movies, it is: Vulnera Sanenteur
Malfoy.
Protego.
Alohomora