I imagine it to be the instructions of mama parrot to her chick, going for a ride. They know the cat is friendly, and the dog is too playful.
We can also imagine it to be the instructions of a father to his child, choosing his place on a carousel.
Two sentences before she told me to not sit on the cat. Make up you mind girl, i cannot stand on my feet all day long, i need to sit on something that doesn't breathe pls.
The duolingo hindi team has done a fantastic job in creating this course, but some sentences can be a little strange like this one. May I suggest an alternative - 'Sit on the chair, not on the table.'
Nouns and pronouns are put in the oblique case in Hindi if they are followed by a postposition. This is true for both singular and plural nouns. For singular nouns: masculine आ changes into ए, the rest don't change. For plural nouns: add ओं
Let's just imagine this sentence is addressing Duo the owl and not a human :)
how come नहीं is used instead of मत ? is it because बैठो is not used once more afterwards?
Correct. कुत्ते पर मत बैठो would be valid but to prevent repetition and encourage efficiency in the sentence, we use the negator नहीं
This might well go into Charlie Chaplin's "Animal Trainer" film, where he is training a flea in the flea circus - बिल्ली पर बैठो, कुत्ते पर नहीं