1- Used to say that you did something very recently:
'I've just heard the news.'
'He was here just a minute ago'.
2- Used also to mean 'simply':
'It was just an ordinary day.'
3- Used to mean 'only':
'He's learning English just for fun.'
'We're just good friends,' she said coolly.'
4- really; completely
'The food was just ownderful.'
5- Used to make a polite request, excuse, etc.:
'Could you just help me with this box, please?'
6- used in orders to get sb’s attention, give permission, etc.:
'Just listen to what I’m saying, will you!'
7- at this/that moment; now:
'I’m just off (= I am leaving now).'
8- just about / going to do sth going to do something only a few moments from now or then:
'The water’s just about to boil.'
9- just around/round the corner (idiom): very near
'His house is just around the corner.'
'There were good times around the corner (they would come soon).'