What is the data that is being synced between Xero & SF. Is it from Xero to SF or from SF to Xero? How does this process work?

What is the data that is being synced between Xero & SF. Is it from Xero to SF or from SF to Xero? How does this process work?

SFX supports two-way sync,

SFX supports Invoices, Invoice payments, Bills(expenses), Credit Notes , and Pre-payments. Customer and Products sync is based on the mapping between Salesforce and Xero