Apple Pay is available:
On eligible devices, which include iPhone SE, iPhone 6, iPhone 6 Plus and newer iPhone models including iPhone X:
In selected countries:
If you are within one of those regions, check that your iPhone region is set accordingly:
On your iPhone, go to: Settings > General > Language & Region > Region.
Also follow all of the required steps here:
Note that it is only possible to add supported payment cards from participating banks or stores within those countries.