"There are rats in the grass."
Translation:घास में चूहे हैं ।
No, में is a postposition, so it is placed after the word/group of words it refers to (unlike English that uses prepositions placed before). Here, में is placed after घास, so it is "in the grass", not "in the rats". I'd translate "Grass is in the rats" by: घास चूहों में है। (anyone feel free to correct me if I'm wrong).