If your talking about Dragon Arena. it means there's someone who appeares but read the
yellow box. Also beat him/her because you will a bonus. for example if you beat cell jr.
you will get him instantly. [whoa that's a long sentence isn't it.]

when someone breaks in it means that,well someone broke in and you must fight them to
unlock a bonus character such as cell jr,or pan (gohans daughter') to unlock cell jr fight
every majin buu at least 3 times and win,to get saibamen fight level 32 videl until nappa
breaks in but you have to be a between level 11 and 20

when soemone breaks in, it means that in dragon arena, you fight a high level person that
you diddnt choose to fight.

When someone breaks in, the Dragon Arena, you have to fight them. If you win, you will get
a reward. The reward depends on who you defeat.