What could this be? NaBr (Sodium Bromide)?

there could be a presence or bromine in the solution. bromine is usually yellow in color unless reacted with organic electrophiles which turns the solution colorless. you could look at some tests for qualitative ysis of the solution. but i think you can only test for the bromine, not sodium because sodium reacts easily with different substances. try getting a sample of the solution then add about 3 drops of a chlorine solution.if it turns yellow, then bromine is present. for the sodium maybe you can do a flame test to determine if sodium is present. if the flame turns yellow or orange then sodium is definitely present in the solution.