"That thing he told us yesterday."
Translation:Den ting han fortalte os i går.
Okay, I'm like very late to this, but since no one picked this up...
It's not a complete sentence here, but just a noun which a dependent clause is attached to. You can add "that" and at to the respective sentence to make it clearer:
"Den ting at han fortalte os i går" - "That thing that he told us yesterday."
A complete sentence would be something like "He told us that thing yesterday", where you will have the verb in the second position in the Danish translation again: "Den ting fortalte han os i går."
I'm not sure the term "prepositional phrase" is right here, but it's also not a complete sentence in Danish, just a noun with an attributive phrase.
In a normal Danish statement, the verb would need to be in the second position, but here it's in the third (after the direct object "den ting" and subject han). A proper sentence would be:
- Den ting fortalte han os i går. - He told us that thing yesterday.