Just a couple of questions

[Harmonica]

Hi

I have recently started playing no limit ring games, and I have seen this play made by some people a few times in a session, where they will be a few limpers in the pot and a person will push all there stack in, what can you deduce from a play like this, do they have a really weak holding or do the have a high pair?. My next question is, I have read on this forum and other ones, people ask what someone's hourly rate is and they have replied something like 5BB's, could someone tell me what this means, is it big blinds or big bets per hour, and if it is big bets, just what is meant by a big bet, is it were you double up?

Thanks in advance