The process is quite simple:

• In your import excel file you just need 2 more excel columns, ORIGINAL TITLE and  LANGUAGE CODE.
• For your initial products this is not a prerequisite – the default language defined in WPML settings page will be used and the ORIGINAL TITLE is not needed.
• You select your Excel file and you just map this new excel columns to the mapping screen – a simple drag and drop or automap (this will work if the label in the excel is the same )

You can view a sample excel file here

Import WooCommerce Product translations for WPML using one of the plugins below and according to your needs