You have been paged because an ESXi host is unreachable. The host had gone down due to a hardware error. Along with it, the host took down a couple of VMs. Thankfully, you have vSphere HA turned on in the cluster and HA restart all the impacted VMs on other hosts in cluster.
Should you want to get a list of impacted VMs, VMware has a KB article.
Find the master node.