Your question is quiet logical.What if the person doesn't have vocabulary.The answer is he has to increase his vocabulary.How?Well through listening and reading.It can be through anyways by reading a simple book,listening to talk shows etc.If you have problems in getting the meaning,then you will have to put in some real hard work.The dictionary should become your best friend.You should start with finding simple words.First try this,then once you start getting active you will find your own ways which suits your situation.
