I'd like to calculate shortest route and distance in QGIS 3.2. In the past I have used the v.net.iso, v.net.distance and v.net.path tools. However, I've noticed that there is no distance parameter there, but cost. If I want to calculate the distance in meters where do I specify this? Do cost mean distance on the screenshot? How do I set it to distance?
[Updated the answer after question was updated]
The default should be distance if you don't input a cost column.
So the field "Cost for isolines" in your screenshot would mean the cost in CRS units if you don't manually select another precomputed cost column.
So your screenshot settings would output a vector file mirroring your input network, but divided into 4 categories (attribute "cat" with values 1,2,3,4).
Since the "Cost for isolines" is set to 1000,2000,3000; "cat" 1 would be 1000 CRS units (meters for example) from your start points, 2 is 2000, 3 is 3000 and 4 is the remaining network.
If you have computed for example the cost to traverse a line segment in seconds in another column (based on a speed limit for example), you can choose that column under Advanced parameters. Then "Cost for isolines" would correspond to 1000 seconds, 2000 seconds and so on.