To me it depends on how important I think this side character would be. If it's a shop owner, worker, a throw away character for a one line in a battle, or the human roadblock stopping my character for that scene I may not give them a full name but a generic first name for the region my characters are in. My regions are loosely based off of actual countries so I can think what sounds like it would be from there.
Otherwise if a name must be given I will ether choose something random like Male%%% speaks to Female@! or use a baby registry that contains names selectable via country of origin and choose the name based off the first letter to pop into my head.
Then I put these into my mastery list of characters with details on who they are and what they were doing to jog my memory of this scene. Like:
Guard Emily - Refused heroes entry into the city.
Guard Male## - Smuggled in heroes on May 14, 1312 for a bribe into city of Rapid Falls.
I also highlight over the bogus names in both the master list & the actual draft story so I can easily spot them for editing later.
You can use places like:
Baby registries like http://www.babynology.com/
Random Name generators like - https://www.mithrilandmages.com/utilities/Modern.php
Or some writing programs under options have a random name generator equipped with them.