The reaction of ethanoic acid with magnesium metal results into the formation of a salt and hydrogen. The reaction could be thought as a reactive metal react with an acid to make its salt and hydrogen gas is released. The reaction is relatively slower.
The reaction of magnesium with ethanoic acid is:
2CH3COOH + Mg →(CH3COO)2Mg + H2
Hence 2 moles of ethanoic acid would react with one mole of magnesium.