The general formula for when a acid reacts with a salt (sodium) is that a salt and hydrogen is produced. This should be learnt off by heart!
So, our acid is Hydrochloric acid, and when this reacts to produce a salt which ends in the word 'chloride' because hydrochloric acid contains chlorine. But the salt also contains elements from the sodium, this means we can work out that the reaction makes sodium chloride and Hydrogen