The main definition and list can be found in the section on Actions.
Free Actions: Some minor actions are “free” and don’t
inflict multi-action penalties. Speaking a short sentence or
two, moving up to the character’s Pace, falling prone, resisting
opposed rolls, or dropping an item are all examples of free
actions.
Page 66 of Savage Worlds Deluxe (pdf copy)
Other free actions include:
- Maintaining powers (Using Powers, page 103)
- Aspects of certain Powers and Edges, e.g. Soul Drain, Quick Draw, Speed
- Switching Firing Mode on a gun (page 72)
- Driving without attempting a maneuvre (page 98)
This list is not meant to be complete, as the rules cannot hope to cover all situations that might come up in a game. The expectation when an unclear situation comes up is that the GM will compare what the PC is doing to the examples in the book, and make a judgement.
As per VahallaGH's excellent comment, free actions are still limited by the "you can't repeat an action" rule. So moving Pace may be a free action, but you can't repeat that action without some special ability or other cost.
Another situation that can come up is when a player attempts a sequence that includes actions that would individually be counted as free. It can get to the point where the player is trying to cram so many free actions into a single turn of combat, that the GM has to make a call. Again, in these circumstances, the actual call is left up to the GM, and may depend on a variety of aspects. For example, I'd probably allow more flexibility in a pulpy pirates game than I would in a gritty, post-apocalyptic zombie campaign.
Best Answer
I believe what you are looking for is on Page 55 of the Deluxe rules.