A state in a State Machine is a set of actions that execute while the workflow is in a certain condition1. Each state has three components: Entry, Exit, and Transition Actions2. Entry Actions are executed when the state is entered, Exit Actions are executed when the state is exited, and Transition Actions are executed when a transition is triggered by a condition3.
References:
State Machines in Studio course, Lesson 1: Introduction to State Machines, Topic: What is a State Machine?
State Machine documentation, States section
How does State Machine work? forum post, Answer by @aksh1yadav

The Retry Scope activity is used to retry the execution of a specific part of the automation in case of an error.
In this case, the properties of the Retry Scope activity are set to retry 3 times with an interval of 8 seconds.
Therefore, if the Work Items button appears on the screen after 8 seconds, the activity will click on the button. References: [Activities - Retry Scope]

The default polling interval for an event trigger is 5 minutes, which means that the trigger checks for new object events every 5 minutes. This value can be customized using the Adjustable Polling Interval feature, which allows users to choose the interval on which event triggers check for new object events. The polling interval can be changed from a specific connector's page or from the Connections tab. (UiPath Automation Developer study guide) References:
How to modify the polling interval for Integration Service Triggers?
Integration Service - Triggers
UiPath Integration Service - Vote on Tutorials

To display the value of a DateTime variable in a specific format, the ToString method should be used with the format specified as a string argument. The correct expression for the "Timestamp" variable to display it in the format "yyyy-MM-dd hh:mm" is Timestamp.ToString("yyyy-MM-dd hh:mm").
References:
Microsoft .NET Documentation: DateTime.ToString Method

The Get Transaction Data state is responsible for retrieving the next transaction item to be processed from the queue in Orchestrator. The state will loop until there are no more items in the queue or an exception occurs. A linear process can be implemented with REFramework by using a single queue item that contains all the data required for the process. (UiPath ReFramework documentation1) References:
1: Robotic Enterprise Framework Template - UiPath Studio.