Adding Translate key in the code

[FloreG]

Hi, 

 

I am looking to translate my website in French. however some module are missing some translate keys in the code. Newsletter doesn't have any translate key and so I can't change it from english to french. At the moment it looks like this: 
{l s='Your email address' mod='blocknewsletter'}

 

Does someone as a clue how to write it in the code ?

 

thanks