As sodium ion has a 1+ charge and it can form the ionic compound NaOH with OH1-, hence it is a lone pair accepter (is this correct?). Therefore sodium ion should be an acid?
According to the bronsted lowry definition of an acid, the sodium ion is not an acid. This is because the bronsted lowry definition of an acid states that an acid is a proton donor. The sodium ion is not a proton donor and so according to this definition it is not classed as an acid.
I hope this answers your question :)