Period

On 5th of pill my girlfriend had a bleed that lasted only like an hour
Is that normal

Depends on how long they've been taking the pill. The advice my gp gave me was that when you start taking the pill it's normal to get "break-through bleeding". However if they've been taking the pill for a long time then this is a bit unusual. If she's worried she should speak to her gp xx

This is her third month! She didn't want a period second month so kept taking as gp advised.. does that make it more normal!

Ah ok, so she's been taking it for three months without taking a break for periods? That can cause break through bleeding too. Three months isn't that long to be on it, and if she hasn't regularly been leaving the gap for a period each month then her cycle hasn't really settled down so it's not that worrying. I didn't want a period during my exams so I didn't leave a gap for three months and got some break through bleeding, because it was going against the natural monthly cycle I was used to. I'd say not to worry too much, but if it happens again or she gets a lot of "spotting" (ie not a full period but random blood coming through sporadically) she should talk to her gp in case it's something more serious.
But yeah that sounds quite normal if she's only been taking it a few months and hasn't been in a regular routine.
(This is just by my experience of taking the pill and advice my gp has given me, I have no medical background particularly.)

She took a period
Then skipped one by continually taking pills then wanted one this month

Should we worry?

Personally I wouldn't worry because by skipping and then allowing it she's not letting herself have a regular cycle, so her body hasn't caught up with it.
But, I am not medically trained, I've just been on the pill for 4 years on and off.
If it doesn't happen again, I wouldn't worry as a bit of bleeding when you're not in a regular routine is pretty normal.
However, for peace of mind it may be worth speaking to a medical professional like a gp or visit sexual health clinic or call 111.