Hi @gkagg,
Open the language file (en-GB.tpl_ja_purity_iv.ini) in the "[root]/languages/en-GB/" folder and go to about line 66, you will see the "TPL_LATEST_STORIES" language string. You can change it by your text.
TPL_LATEST_STORIES = "'S Latest stories"
Or from you site's admin go to the "System -> Language Overrides" menu. Create new override for language string (PL_LATEST_STORIES).