As a Verb or Adjective:
1. To be available to someone without them having to pay for it. English = (be) free.
2. To be done willingly and because you choose to do it and not because you have been forced to do it. English = (be) voluntary.
As Modifier:
1. Used immediately next to a verb to mean the action is done without any cost. English = freely.
2. Used immediately next to a verb to mean the action is done willingly and because you choose to do it and not because you have been forced to do it. English = freely, voluntarily.