This question needs to be refined further to truly get the answer for which you are looking. As it stands, I can only give you a generic answer. When thinking of the advantages of hiring, several ideas come to mind. Fresh thinking and approaches can bring successful ideas to a new company. Another idea is the spark new partnerships can provoke, thus preventing the company from getting stale. In looking at disadvantages, think about the opposites of the positives. With a new hire comes training and time to explain procedures. A new group dynamic has to be created so that the group functions to the best of its ability. With whatever industry you are working with, a new employee creates both advantages and disadvantages. Now develop your own ideas, and your essay should work.