What exactly is dropping?

I had my 32 week appointment today and doc said from what he could tell by the heartbeat, baby is head down and in the proper position. Is this what dropping is? I'm a FTM and didn't think to clarify. Also, while he was measuring he said, "Looks good, you're measuring 35 weeks." I honestly thought it was a slip up and he mean to say 32 weeks so I didn't correct him. If baby is head down does this mean he could be measuring ahead? I don't even know what dropping is! (I know I know, I should always clarify but sometimes it goes right over my head 😑