The junk mail button and the garbage button do not appear in my mail.com account. Where are they?

Hover your cursor on the Favorites header in the Mail app sidebar, then click the Add (+) button that appears.

Select your Junk and Trash mailboxes to include them on the list.

Mail User Guide for Mac - Apple Support

do you mean the buttons on your mail toolbar?

if yes, go to Apple Menu > Mail > View and choose "Customize Toolbar".

and in the resulting window, drag and drop your desired buttons to the toolbar.