This is no doubt a most elementary question. Perhaps context is relevant.

Specifically someone said there is a $70$% chance the US stock market will take out the March lows in the next six months.

I can understand a statement such as the probability of having a particular disease given a positive test result when the sensitivity of the test, false positive rate, and presumed proportion of the population effected are taken into account.

But I am not sure how to interpret a stand-alone remark such as I am referring to.

I am not interested in what the person meant. Rather, what should someone who is cognizant of probability and statistics intend to imply when they make such a statement.

I assure you I am not looking for investment advice or any corroboration or refutation of the remark. I only mention the context as it is not like tomorrow's weather (maybe based on today's) or something one can extrapolate.

Thanks