Russell is arguing that philosophy is valuable. You'll want to think about his argument using his own key ideas:
•How does he think philosophy is different from science?
•Does he think philosophy is different from science in a good or bad sense, like one is better than the other, or that they are just different methods each worthy in their own way?
•When he talks about things like "prejudice" and "common sense", what do you suppose he means?
According to Russell, philosophy is different from the science in terms of their respective utility. The value of the study of the science lies in practical application of benefiting everyone, but the study of philosophy directly benefits the student himself.
Russell think philosophy is different from science in a good sense though he admits that philosophical pursuits have yielded very little definite knowledge. However, it is not the uncertainty surrounding philosophical questions that their study remain valuable, but rather because of it, Russell argues, it forces the student of philosophy to become more imaginative in his/her intellectual pursuits, while at the same time making it less likely that he/she will cling dogmatically to unchallenged assumptions and beliefs.