/System/Library/Frameworks/NetworkExtension.framework/PlugIns/NEIKEv2Provider.appex/Contents/MacOS/NEIKEv2Provider NEIKEv2Provider is a service responsible for establishing secure VPN connections. It requests access to the Keychain in order to receive authorization data required for the VPN connection to be established. NEIKEv2Provider uses the IKEv2 (built in VPN protocol on Mac).
The binary is a part of NetworkExtension public framework.