There's a brief explanation at [0]. (Note that "1RZ" is understood to be a halting transition, since state "Z" has no rules.) Wikipedia also has a more elaborated example of a TM state table [1]. You can see the trace of this particular TM at [2].

[0] https://bbchallenge.org/story#turing-machines

[1] https://en.wikipedia.org/wiki/Turing_machine#Formal_definiti...

[2] https://bbchallenge.org/1RB3LB1RZ2RA_2LC3RB1LC2RA_3RB1LB3LC2...