Objects can be placed behind some other objects and visually are hidden. They are accessible only from the layers panel. User do various workarounds like cut the object and then make edit and finally paste it back on the canvas. Another option is to turn off the visibility of object but this can be difficult when the file houses many layers and objects nested with in it.
In the following video, I showcase you the presence of "Select Behind tool" which will let you select the object behind an existing one, sub-selecting it, moving it, nudging and making edits to it.