Left to Right means that the evaluation is done left to right. For example, 2+3+4 -- obviously, Java can't do both additions at the same time, and they have the same precedence. It is however, left to right, so the left addition is done first.
where both the ?: operators have the same priority but associate to the right, the compiler evaluates the bit on the right (345 or 657) before offering that result as an alternative to the bit on the left (123).