The main advantage of using real objects into the classroom is to make the learning experience more memorable for the learner. To give a couple of simple examples, if you are going to teach vocabulary of fruit and vegetables it can be much more affective for students if they can touch, smell and see the objects at the same time as hearing the new word. This would appeal to a wider range of learner styles than a simple flashcard picture of the piece of fruit or vegetable. (With very young learners, classroom management can become trickier if you bring in real objects as excitement levels tend to rise. Last year one of my students bit into an onion we were passing round. I’m sure he hasn’t forgotten that class!)
A second example would be if you are going to teach some functional language for asking for the timetable for a train. You could use a fictitious timetable or you could use a real one from the local train station, one from the internet, or if you’re really organised, some you brought back from your last trip to the UK. This way you expose students to more language than simply the times and destinations. They will see information about prices, discounts, bank holidays etc.