The first card in the reading is the Three of Cups. This card symbolizes self-efficacy and the need to control one's destiny. So, in relation to the question, this implies that your best friend believes that she is in control of the situation and can decide whether or not she gets into a relationship with this guy. On a deeper level, this card suggests that your friend is confident in her own judgment and ability to handle the situation.
Secondly we have the Nine of Pentacles. The Nine of Pentacles indicates a strong desire for emotional stability and security. So, from a conscious point of view, this card suggests that your friend is looking for a stable relationship with this guy. She might even be willing to build something more lasting with him.
Finally we have the Two of Wands. This card represents resourcefulness and creativity in dealing with difficult circumstances. So from a superconscious point of view, it suggests that your best friend is ready to face the challenges that can arise in a relationship with this guy. It also shows that she has confidence in her ability to overcome any obstacle.
In conclusion, it can be said from the three cards drawn that your best friend has good intentions regarding this relationship and seems to believe in her abilities to handle it properly. She also feels secure enough to deal with any problems that may arise in the relationship. So while we can't know whether or not the relationship will work out, it appears she made an informed decision based on her self-efficacy and her desire for emotional stability.