There are two possible scenarios the validation panel can show you.

The first scenario is when there are no validation errors.

When there are no errors in your model (e.g. incorrect link of two objects, no start or no end of the model, etc.) the validation panel will show the message No validation errors. 

The second situation is when there is at least one error.

In case you have no start or no end of a Model, an error message is displayed this panel. When you click on the error, you will be redirected to the object that is incorrect.

You can turn on the validation in the toolbar. When you turn on the validation, all the errors will be highlighted red in the model.

When you click on the error in the Validation panel, you will be redirected to the error on the canvas, and vice versa.