Let’s learn Japanese with manga. What you are going to learn on this page is:
(I am an ordinary man.)
オレ means ‘I’. It sounds a bit rough and used by men only. は is a topic marking particle and does not mean anything.
普通の（ふ・つう・の）means ‘ordinary’. 男（おとこ）means ‘man’.
なんだ is same as です which means ‘is’. なんだ is much more casual than です and used by men only.
If you are a girl and want to say ‘I am an ordinary woman’, you should say 私は普通の女なの.