In the case of a failure of a host, surviving ESXi hosts take over and reboot the affected virtual machines on themselves. A failure could include host power loss, kernel crash or hardware failure.
Note:
BEST PRACTICE: Everpure recommends leaving host monitoring enabled.
Host monitoring is enabled by default when vSphere HA is enabled. Everpure recommends leaving this enabled and has no specific recommendations for its advanced settings (see VMware documentation here).