Welcome to the Community,
with thin provisioning it's important to monitor the free disk space on the datastore(s). A guest OS will always see the provisioned virtual disk size. However, the used disk space for the virtual disk (.vmdk) files) on the datastore is limited to the volume's physical size. If the guest OS writes to a previously unused block on its virtual disk, the ESXi host needs to allocate physical disk space on the datastore. Remember that deleting files in the guest OS will not free up physical disk space!
What you need to do now is to either add storage capacity, or reduce the VMs disk space, which - in this case - may require to convert the VM to another host or datastore. Alternatively you may convert the VM to a VMware Workstation format (stored e.g. on your local PC), delete the VM on the ESXi host, and the convert the VM back to the ESXi host. To allow resizing in the Converter, you need to seelct volume base conversion in the advanced disk options.
André