1） It will be open 24-7. 这里全天营业！

24 means 24 hours a day

7 means 7 days a week

So here the whole sentence means that a shop or a store will be open for the whole day and night, which will bring great convenience to us.

当然可能还有一些网吧也会全天营业！

For Andy, I don't like to stay up!

Reason:It will waste time, energy and money! ^_^

2） It is six pm. on the nose!

on the nose: just 正好

we can also say: It is 8 am. on the nose! Now let's begin!

当然nose还有其他的用法，大家一定要注意多查字典哟！

e.g.

lead sb. by the nose: 控制某人！

Finally, 360abc.com wishes you a happy and sweet day!