I have been tasked with creating a vlan on a HPE 1920 switch that has no access to the outside world but can access all other devices connected to the switch, how do I go about this? I have some limited experience with Cisco routers but none with HPE.
A VLAN is a Virtual Local Area Network, i.e. a layer 2 network.
Hosts within a LAN (being it Virtual or not) need a router to reach other networks (other VLAN or outside world). I.E. a layer 3 network.
So what you need to do is configure access-lists on the router that tells which networks the hosts from this VLAN are allowed to communicate with and forbid all other communication.