Appears to be an for a Cisco IOS Virtual Image, likely used in VIRL / CML (Cisco Modeling Labs) or EVE-NG / GNS3 .
The string you provided:
Would you like help the correct image format for your emulator? vios-adventerprisek9-m.vmdk.spa.156-2.t
vios-adventerprisek9-m.vmdk.spa.156-2.t