What does this idiom mean? 'To get the ball rolling'

you have to do something now, before further progress can be made

to start an activity and get others to join in

to tell someone honestly what you think or what you plan to do

What does this idiom mean? 'The ball is in your court'

to go back to the beginning of a project, because previous attempts have failed

What does this idiom mean? 'To put your cards on the table'

What does this idiom mean? 'To be on the cards'

What does this idiom mean? 'To go back to square one'