I am sure this can be done using Translation workbench, but do not know how to find the setup component that I want to translate. All tabs, buttons, static text need to be translated.
First enable it by Setup - Translation workbench - Translation settings - Activate it.
Assign translators by adding new language and user.
Then you can add translation for setup components by,
Setup - translation workbench - Translate - choose the language - select the setup component - object and double click on the label translation and paste your translated texts there.
Repeat the same for all setup components. For plain text translation use custom labels.