Is this wrong?
I read that your not suppose to end a sentence in Spanish with a prepostion. Does that mean a one word prepostion is a no no, or a prepositional phrase?
She placed her gun and badge on the table. is that ok, or do you have to say "On the table, she placed her gun and badge"
3 Answers
For English (but that was not your question) skygoneblue's answer is correct. For Spanish, it's entirely possible/reasonable to end a sentence with a prepositional phrase (e.g. No sé a dónde vas." but in Spanish (as in English) prepositional phrases are introduced by prepositions (the preposition is the first word not the last in the phrase. As to it's being a "rule", it's more of an observation; if you manage to construct a sentence that ends with a preposition (not a prepositional phrase), it will sound exceedingly queer to Spanish speakers (since they don't).
And, the rule about not ending sentences in English with prepositions is merely prescriptive (ie: it's just a "should" - it's not a rule).
That whole notion is only stemmed from the belief that the Latin language is perfect, and that English should mirror its perfection. Obviously that belief has many holes in it, but that once-upheld doctrine of not ending sentences with prepositions hasn't been entirely laid to rest.
Long story short: If someone gets on your case for ending a sentence with a preposition, they have some learning to do. 
Oh it's fine to end a sentence with a prepostional phrase. That happens all the time.
Voy a la tienda con mi esposa. I am going to the store with my wife.
"Con mi esposa"is a prepositionl phrase, beginning with the preposition, con.
What you can't do in Spanish is end a sentence with a preposition:
Con, de, por, para, según, sin, etc.
We do that sometimes in English: "Show us what you're made of." I don't think it's the best usage in English, but it's apparently out of the question in Spanish.
