You can use it if someone bumps his head for example and he feels afterwards dizzy, lightheaded.
Or someone is stordito, more figuratively, for example if he just heard an upsetting story and he doesn't know how to behave or what to say. Or if someone has just got out of bed and is still a bit sleepy.
"dopo la notizia che Luca è morto mi sento un po' stordito"
"sono solo le 5 del mattino, sono ancora stordito dal sonno"