There is a more readable state table but each underscore separates a group of transitions for one symbol, writen as groups of 3 characters for each symbol. These are the symbol to write, new state and direction to move. The --- state halts.
Click on the link in the article [0] and you'll get a page that expands it to a human readable table. Each current (state, tape value) pair maps to a (new tape value, direction to move tape head, new tape value) triple.
https://bbchallenge.org/1RB2RA1LC_2LC1RB2RB_---2LA1LA
For example: If in state B and the tape at the current marker reads 0: write 2, move the head Left once, and go to state C.