It is impossible to describe all Tk widgets here in detail, but an overview of the widgets and their most common application is a good start for further exploration in the Tk manual. Frames contain other widgets. Buttons cause a specific action. Labels display short texts. Text objects provide text browsers and editors.
Scroll bars let the user scroll through large list boxes, large texts, etc.
Canvases permit almost arbitrary graphics displays. Menu buttons and menus create pop-up menus. There are also various image objects to display drawings, photos, etc. For more information about these widgets, see the Tkinter documentation and the Tk man pages. Instead of typing the filename, a file browser can be used.