Nick here from Shopify.
If your store's based in a country where Shopify has supported credit card payment providers, which Saudia Arabia is, then you can use Shopify POS You can see the gateways Shopify is partnered with in Saudi Arabia here. Regarding the POS side of things, there are two important considerations:
Shopify has a helpful guide with some more information about hardware also which you can see here.
Do you a specific question about the hardware installation? If so, let me know here and I can see if the retail team can shed any further light on it.
Looking forward to hearing from you.
All the best, Nick