Explanation
The Show Elements button in the Computer Vision wizard is used to toggle the highlighting of all UI elements that have been detected by the Computer Vision engine on the target application. This helps to visualize the accuracy and scope of the UI element recognition and to select the desired UI element for automation. (UiPath Automation Developer study guide) References:
Computer Vision
Computer Vision Wizard

Explanation
The recommended type of workflow for designing a complex business process using UiPath Studio is Flowchart. Flowcharts are suitable for a more complex business logic, as they enable you to integrate decisions and connect activities in a more diverse manner, through multiple branching logic operators. Flowcharts can also be used as a part of other diagrams, such as Sequences or State Machines3.
Flowcharts provide a clear and visual representation of the flow of the process, as well as the possible outcomes and exceptions. Flowcharts can also be easily modified and expanded, as new activities and branches can be added or removed4. References: Flowchart and Understanding the Concept of Workflow of UiPath from UiPath documentation and Medium.

Explanation
This LINQ query is used to group the rows in the table by the "Item" column and then find the maximum sum of the "Quantity" column for each group. The result will be the maximum total quantity for any item in the table. (UiPath Studio documentation1) References:
1: LINQ Queries - UiPath Activities.

Explanation
The recommended method to ensure the selector identifies the correct PDF to use is to use the * wildcard character in place of the "X" in the title attribute value. The * wildcard character is a symbol that can replace zero or more characters in a string. It can be used to handle dynamic elements in a selector, such as the title of a PDF file that changes for each report2. For example, if the selector for the PDF file is:
<html title='Report X - PDF' />
Then the selector can be modified as:
<html title='Report * - PDF' />
This selector will match any PDF file that has a title starting with "Report" and ending with "PDF", regardless of the number in between. This way, the selector can identify the correct PDF file to use, even if other PDF files are open on the desktop, as long as only one report is open at a time.
References: Selectors with Wildcards and Wildcards in selector from UiPath documentation and forum.