What languages are supported on the payment form?

SecurePay is language agnostic.  By default there are 25: en, de, fr, es, it, nl, dk, fi, se, tr, ja, sl, pt, pl, cz, hu, bg, ro, ru, cn, gr, no, sk, ar, ko. But it is possible to change the text value of the labels to anything you choose using the SecurePay API.