What does the arrow on VCC in a BJT bias circuit mean?
The arrows have no special pointing significance. The conventional symbols used on schematics include the use of the arrow as a symbol for a power supply connection.

If you look around you will notice that there are a variety of different symbols used for power supply connections on schematics. There are also various ways that the associated voltage rail are labeled. Here is a sample of some of the common types. Note that in my example there is no particular correspondence between the label type and the symbol used. This is by no means an exhaustive list either and you can find other usages as well.