This move is usually played for some special tactical advantage. Purely for strategical reasons this move is bad because it gives the opponent an ideal cut. 'a' instead of 1 is the "strategically correct" hane in this shape.
White is almost certain to cut.
Black will probably play one of the lettered moves.
Hanedashi is a Japanese go term in common use in the West. The alternative expression hane inside is less widely used.