'My view' is a stored list of components, which functions like a selection basket.
The 'plus' button to add elements to My view.
The 'minus' button to extract elements from My View.
The 'equal' button, currently selected items (in the model tree or the 3D window) will be set as My view, and replace any elements which might have been part of the selection basket earlier. If nothing has been selected when clicking on the 'equal' button, all visible elements will be added to My view.
To show the selection of elements which has been added to My view, go to My view > Show My view.
You can also run Smart views on your active My view. Right click on the Smart view you want to run, and choose 'Show for My view'.
At the bottom right of your screen you will see a counter for the amount of objects in My view.
📝 Note: Hold down ALT during 'My view' operations to modify the view set without visualizing it in the 3D view directly.