The Inter-VLAN routing option means it will allow/disallow (checked/unchecked) the communication of the devices on that particular VLAN to other VLANs.
If you need the devices in one VLAN to be accessible by devices in other VLANs, inter-VLAN routing should be enabled on all VLANs.
If inter VLAN routing is enabled it blocks traffic to (and from) that VLAN to (and from) other VLANs that have inter-VLAN routing enabled.
For more granular control between VLANs it is recommended to use the Internal Network Firewall Rules on the device web admin GUI or InControl.
Read the section on InControl firewall rules for additional information.