@ppr have a good sample example of using Linq with Uipath here. see below
[HowTo] - First Start with LINQ (VB.Net) - News / Tutorials - UiPath Community Forum
And if you want to learn more. They are good place to get started.
Language-Integrated Query (LINQ) (C#) | Microsoft Learn
LINQ Tutorial (tutorialspoint.com)
Happy learning