Wondering

Okay guys I have a question how can you tell if it's a boy and girl on the U/S as far as I seen I look on my very first one I haven't gotten m second one yet due to me moving and now going 5th of August to get me another and find out what im having since I'm far along in my pregnancy and only have 2 months to go I see that everyone can tell by the HZ of their ultrasounds on either it's a boy or girl okay my fist one says 14HZ1 what does this mean