Currently you would need to create 2 articles, 1 for English and 1 for Arabic.
That said, translation of custom content is planned to be integrated with the completion of phase 3 as far as I know, but since we are not there yet, you need to either create 2 articles (1 for every language) or split the FAQ article eg. with a line or so to show first the English article and below the Arabic translation or vice versa.