After the speech there will be a 'question and answer session'. [=a period of time when people can have their questions answered]
School will be back 'in session' at the beginning of September. [=school will start again at the beginning of September]
The board met in 'closed session' [=with no one else present] for four hours to discuss the issue.
(..) been out now, Reverend? Let's see. Almost two hours now. I think that's an awful good sign, don't you? Court's now in session. Everybody rise. Gentlemen of the jury, have you reached a verdict? We have, Your Honour. Will the defendant please rise (..)1962 To Kill a Mockingbird
(..) -Yes, I am. Thankyou, BrotherJoe, for holding my seat. Come on, children. Come on, come on. This court's now in session. Everybody rise. On the night ofAugust ... I wasjust leaving my office to go home when Bob-- Mr Ewell-- came in. (..)1962 To Kill a Mockingbird