Translate metatags blog posts

Hello,

I need to translate the metadata of content-single with template blog enabled from english to french. I’ve been trying to translate in ”content-single.php and ”function.php” but I cannot do it When I translate the text, I get a blanck page for each post. How can I do it? I won’t be able to use Zerif-Lite if I cannot translate the meta into french!
Thanks in advance