Hello hector.editor98,
Thanks for reaching to us.
1. If you want to change default Product labels:
+ In order to change / translate words. Please make sure you synced the strings first before changing / translating WooCommerce, WoodMart Core plugins and WoodMart theme. You can refer to article https://xtemos.com/docs-topic/theme-translation/
+ You are also need to select the language for the backend and theme settings for admin from the admin user profile, please edit the user’s profile and then select the language for that user it will show the same on the backend.
2. In order to create a custom label, navigate to Products > Attributes > create attribute > then add terms to created attribute – https://prnt.sc/tqzG6kgJCwEQ, https://prnt.sc/yq_ZcONu22_n
Edit the attribute itself – https://prnt.sc/ExOeF6K7T_U3 and enable the Show attribute label on products option – https://prnt.sc/7vckb4xRhteN
Edit the product for which you want to show the custom label and assign that custom label attribute to the product – https://prnt.sc/QGfKsahh3O9a
As a result the custom label will be shown. https://prnt.sc/Oepo-lw1A_l7
Best Regards