"There is love inside you!"
Translation:יש בתוככם אהבה!
יש זה אהבה בתוך ... is my translation. ...just the same ? ! Or does there exist a rule for the position of words ?
I hope someone responds to your syntax question. The prepositional phrase בתוככם goes before the noun. I'm not sure if that's idiomatic or if the syntax is somewhat more fluid. Your sentence doesn't work for other reasons, however, including that with אהבה you would need fem. זאת and the preposition has no object--it's just the base preposition. So your sentence makes no sense grammatically even though your question is good.
This one בפנים is generally (not always) used to mean "indoors" and בתוך means "inside."