Translation:There must be a trivet under the pot when it stands on the table.
Yes, in Danish we do say "står" instead of "sits"? It is different from language to language, so if you want to learn the language, it is important to know these things. It is also perfectly fine to say "gryden er på bordet", but I believe that they try to exemplify this, in order to teach the difference between Danish and English.
So, how come our two trivets are made of metal? I think you will find it is perfectly possible to have metal trivets. Here's a picture to prove it. https://www.argos.co.uk/product/1239935 I do wish people would not post what they don't know about. It can mislead learners of English.