The folktale which roughly translates as The Sparrow with the Split Tongue  is a fairly traditional tale with a message or moral.

The woman is portrayed as cruel and uncaring whilst her husband is hardworking and kind.

...the sparrow becomes his beloved pet, much to the frustration of his greedy and trouble-making wife. She becomes jealous ...

He is also humble; hence, he chooses a small rather a large 'treasure' chest when it is offered to him. The small chest contains  gold and jewels and, after his wife has finished shouting at him because he was away from home so long, she berates him for not choosing the large chest which presumably would have contained even more gold and jewels.

As an overbearing person she intends to claim her own 'treasure' chest and she visits the so-called 'sparrow maid,' who is apparently a transformation of the sparrow to which she was so cruel, demanding the same privileges shown to her husband.   

She gets her just deserves and, having chosen a large chest, as you would expect - she finds it full of poisonous snakes. Ironically, they bite and kill her.

This is ironic because the very thing she  expected to benefit from turns out to be her undoing. The irony extends to the fact that people are self-serving and often do not see their own faults.  

The reader probably does expect that there will be something nasty in the chest as  the wife has been portrayed as  NOT deserving of the finer things in life due to her attitude and selfishness. She must get her just derserves.