4-4 point, low-high double approach
Note that this position most often arises when is played after and not the other way around. If is already there, following up with a double high kakari at a is a common severe move. Black may follow up with a, b, or c.
Both White's stones are working hard here. The stone creates an open skirt in the corner. meaning that Black cannot so easily take corner territory; while blocks Black's development.
As is always the case for double approach positions, Black first needs to pay attention to moving out into the centre.
This is a joseki sequence. might be at either of the marked points; now, sometimes Black can play tenuki.