Hi,
If you are trying to set the translation for your custom module, you can set it from
Enable debug mode -> settings -> Translation -> export translation

Then you can choose the language from it, and select your module to add translation

Replace the language with the language in which you need to translate and export the file.
Afte
exporting a PO file will be generated, Inside that file you can make
changes for the fonts that you need to add translation, after add
translation you can import the saved files from settings -> translations-> import translation Or you can add the file in your custom module /custom-module/i18n/.po

Hope it helps
Code should be:
<label for="field_name"/>
<div class="o_row">
<field name="field_name"/> <span>months</span>
</div>