The DS has the same meaning as character"SPH". And it means that you needn't correct vision. For example, if you find DS under CYL, it means you have no astigmatism and 0.00 is the option required to choose. Also, SPH, PL are all stands for no correction needed in this value entry. In fact, you needn't trouble yourself with these figures. Just give your prescription to an optician, S/he will know how to deal with your prescription eyeglasses.
Well, ds is telling u there is no cylinder or axi except your sphere number. Actually, this doesn't matter a lot cuz u just follow the professional guys's advice and they will prepare everything for u. Besides this, there are several professional terms that are in relation with prescription glasses such as pwr, os and so on. U don't need to feel puzzled.