In "New Moon" Edward tells Bella that he doesn't want her to come with him when the Cullens move. He also asks her: "Please, don't be reckless. For Charlie's sake." After suffering for months Bella begins to pull herself back together by working with Jacob on motorcycles. She has discovered that anytime she tries something "reckless" she can hear Edward's voice.
Of course Bella is imagining this. Edward is many many miles away and he is not talking to her in reality, but she can hear him so she continues to try reckless activities to feel closer to Edward. She does everything from riding motorcycles to cliff diving. These are the only times she can feel close to him.
"One night, she discovers during an encounter with some dangerous strangers that she hears Edward’s voice in her head. Despite her fears, she begins seeking danger in order to hear him again."
Bella only imagines/ hallucinates Edward. Edward is always concentered about her safety and sometimes it makes it him super protective. Since Edward left Bella's life she discovered that she can make Edward "appear" when she does stupid things that put her life in danger. So now in order to "see" him she puts her life at risk.
She just imagines it. Because when Edward leaves her she tries to hold onto him as much as possible. When Edward leaves he asks her not to do anything reckless.., And because she is angry with Edward for going, and leaving her and for breaking her heart he does exactly that. She does reckless and irresponsible things and it turns out that she sees him when she does reckless things.