Hello yassine, 

Thank you for your purchase!

The strings can be 'translated' (in your case just changed in the same language) using  POEDIT or Loco Translate easily, but if you change them in these files this will be applied to all same strings in Amelia. So, you will not translate a new language but take the files with the English language and 'translate' there strings that you want to be different. 

Note: If you change some strings this way, you will need to replace these files after each update of Amelia.

But not sure on what 'Price' word exactly do you mean, since on the event there is only a price (in numbers) not a title price. If you mean on this - the numbers and 'Free' - you can hide it with custom CSS, just add this on the page where you have your Amelia shortcode: 

 <style> div.am-event-data > div.am-event-price {display:none !important;}</style>

Hope this helps, 

If you have any further questions or concerns feel free to ask,