To Sidebar is just to have a confidential discussion - similar to when we go off to caucus, but we do it together rather than separately.
TA stands for "Tentative Agreement" and is when both parties come to an agreement about something and give it an initial (and literal) sign off. Consider it on the "done for now" shelf until the contract goes to membership to formally vote on.
Ground Rules are a common bargaining practices meant to set standards for both parties further defining "bargaining in good faith" beyond how it is defined in law. Beyond your normal group norm setting you might have done in teams, these ground rules carry the heft of a potential Unfair Labor Practice (ULP) complaint if violated.
Bottom line- if the ESD doesn't bargain in good faith with us, we won't let it slide.