Often attributed to Seneca; this phrase means "To err is human, but to persist [in error] is diabolical."
To Err -Make mistakes- is human, right?
But we as humans also possess a consciousness [I am using this term in a very large context, as a neuroscientist, its more complicated , but I will not debate this topic here].
This " consciousness " helps us to decerns the good from the bad and that's how we can judge that that specific action was an error/mistake.
In science, its called trial and error.
Same thing, you make an experiment, try to test a hypothesis, make a mistake, try again.
In life, its very similar in my opinion, We make a mistake or misjudgement of a situation, realise it was not okey, and then we are supposed to learn from that mistake and not repeat it.
Its a very important concept in evolution, isn't it? this how you survive/d.
You and your friend approach a snake, your friend get bitten by the snake and get sick. You know that approaching the snake was an err