Hi,
Payment gateways will treat currencies as you set it, that is “Frs” in your example. However you should check if your currency is supported by PayPal. If it’s not – WooCommerce will just hide PayPal gateway from your customers. I’m not 100 percent sure, but I think PayPal supported currencies are: AUD, BRL, CAD, MXN, NZD, HKD, SGD, USD, EUR, JPY, TRY, NOK, CZK, DKK, HUF, ILS, MYR, PHP, PLN, SEK, CHF, TWD, THB, GBP, RMB, RUB.
Hope I made it a little more clear. Please let me know if you have any questions.
Best regards,
Tom