Azure VPN NAT (Network Address Translation) supports overlapping address spaces between your on-premises branch networks and your Azure Virtual Networks. NAT can also enable business-to-business connectivity where address spaces are managed by different organizations and re-numbering networks is not possible.
VPN NAT provides support for 1:1 Static NAT and 1-to-many dynamic NAT.
Check out the following documents for additional information:
NAT on Azure VPN Gateway.
How to configure NAT on Azure VPN Gateways.