Can you explain dirks splinters?? Like I never quite got what he was referring to, if possible please explain in detail

Dirk’s main self and dreamself can both be awake at the same time.

Lil Hal is a copy of Dirk’s mental self at age 13

Brobot and to a lesser extent, Lil Seb are robot versions of Dirk.

Brain Ghost Dirk is a version of Dirk conjured by Jake’s Hope powers.

So that’s 5 or 6 different individuals, all with a little piece of Dirk that can all be doing stuff at the same time. No other living person (aside from temporarily Time players) have that many versions of themselves running at once.