O HAXM é o Intel Hardware Accelerated Execution Manager, acho que o Android Studio SDK tentou instalá-lo.
"Intel® Hardware Accelerated Execution Manager (Intel® HAXM) is a hardware-assisted virtualization engine (hypervisor) that uses Intel® Virtualization Technology (Intel® VT) to speed up Android* app emulation on a host machine. In combination with Android x86 emulator images provided by Intel and the official Android SDK Manager, Intel HAXM allows for faster Android emulation on Intel VT enabled systems."
Se não estiver instalado tente instalá-lo manualmente .
O emulador deve funcionar sem haxm, mas será muito mais lento.