it is an acid, also known as vitamin c
Because when you add it to water, the pH will be less than 7, making it a weak aqueous acid.
The pKa of ascorbic acid is only 4.2, so it is a weak acid. You can calculate the percent dissociation of a 0.1 M ascorbic acid solution using its Ka, and you will find that it is a small value.
It is an organic acid
Ascorbic Acid is C6H8O6 Citric Acid is C6H8O7