Procedure blocks are helpful when you use the same set of blocks more than once in your app, to avoid duplication
Procedure blocks can have inputs (also known as arguments) which you can add by selecting the blue settings button. Usually you define a procedure in your app and then call it when you're ready to use it in your app.
In the above example from the sample app Thunkableagram: AI-powered Instagram, the procedure is named updatePost1 and encapsulates a number of events that will run when this procedure is called
The example above shows how a procedure is called like any event