How does (first'') works?

dict:abc!((enlist 1; enlist a);(enlist 2;enlist b);(enlist 3;enlist c))
q)(first’‘) dict
a| 1 a b| 2 b
c| 3 `c
q)(first’) dict
a| 1
b| 2
c| 3
q)

How does (first’‘) work, please? And then how would (first’‘’) work?
Thank you!

https://code.kx.com/q/ref/maps/#each

' operates the same as each in these cases

 

 

(first’‘) dict a| 1 a b| 2 b c| 3 c {first each x} each dict a| 1 a b| 2 b c| 3 c (first’)dict a| 1 b| 2 c| 3 first each dict a| 1 b| 2 c| 3