Stone Free is a Stand that grants Jolyne the ability to unravel parts of her body into string. This makes it a very versatile Stand, enabling her to listen in on communications as well as escape and hide by unraveling parts of herself into string.
When she assembles the string, Jolyne can properly materialize Stone Free, partially or entirely. Stone Free is an humanoid Stand which has comparable physical prowess to the strongest Stands.
Jolyne's greatest asset is her imagination. The versatile power of her Stand allows her a wide range of moves which she extensively use. For example, when Pucci used C-Moon to invert Jolyne's body, she used Stone Free to create a "Mobius Strip" rendering her effectively invulnerable to its power.
True to any other Joestar, Jolyne is particularly adept at using whatever presents itself to her advantage, among others the environment and the enemy's power. Jolyne's quick thinking has allowed her to prevail against enemies.
Jolyne combines her tactics with a high level of recklessness, often endangering herself to surprise enemies with an unanticipated move. The particular nature of her power nonetheless assures that she can shrug off some of the damage ordinary Stand users cannot risk in a fight.
Jolyne's intelligence is intuitive to a degree, as she often shrugs off some of her moves as dumb luck, although it is a valid interpretation of her actions.
Hand to Hand Combat
She has also shown to be capable of defending herself, seen in full detail against Officer Westwood. She has extensive knowledge of self-defense, which she demonstrates throughout the series, notably against Pucci.