yet another question about HRM: sportline 670?

Sorry that this may have been addressed already...
I am looking for a HRm because like most.I want to know my actual (or very close too) burn is. I've heard a lot about fitbit and polar, but I have an opportunity for a sportline 670 for women. everything sounds like gibberish when I try to understand about HRM. I am still relatively new to the finess/weight loss game and have been making changes to ensure I am doing it right. Can anyone explain in plain language if this may be suitable for my needs?