ilaria, Whoever wrote this doesn't have a very good opinion of women. Don't let the beast into your heart. I'm talking about woman.

Translate to which language? It looks like some sorf of joke, though I can't say for sure without seeing the context. It says: "Dont let an animal get into your soul (or maybe it's better to say "your heart" here). And by the animal I mean a woman".

I do know what I'm dealing with, I didn't choose it, I have to translate it for an exam.

Ilaria, I think that you are dealing with very metaphorical texts while posting ur questions here. I guess u came across this sentence in a fiction book with a highly sarcastic connotations. The translations have been already provided below, so I would like to point out that u should be very careful with the above mentioned metaphor (comparing a woman to an animal) and never use it in ur speech, as this comparison is very offensive and rude.