An "act" is another word for a performance. So, what does it mean if you tell someone to get their act together?
Get Your Act Together 有条不紊地行事
Anna: Okay, Dan. Let's get this right for the presentation tomorrow. Our 3rd quarter earnings went up five percent!
Dan: No. Our 3rd quarter earnings were down for five percent. Our 4th quarter earnings went up.
Anna: No, Dan. Our 4th quarter was bad. Get your act together.
Dan: Me? Your numbers are all wrong. Get your act together!
To get your act together means to get organized or to take control and deal with something. It's not exactly a nice thing to say to someone. Dan and Anna really do need to get their act together before their presentation.