Ideas on what to do with this space?

Hi! I'm new to gardening (help lots with friends gardens but never had one myself) and was wondering what I could do with this below ground space outside my window :0

Edit: as many of you have pointed out this place is a bad area to grow things and should stay as a cleared out firescape. Ill trust the wisdom of the crowed and not temp fate, thanks everyone for being polite with my misunderstanding of the area!