That is a quick response pendant head so it sprays out and down, in an umbrella shaped pattern. If the curtains are not closed it will be ok. That sprinkler head is over the window for a reason. For example, if the building is close to a property line fire rated windows could be required. Having a small fire rated window with wire glass is not desirable, so an alternative is a regular window with a sprinkler head over it. A place where I see it often is airport terminals. With airplanes outside, fire rated windows are required. Alternatively, they use large regular windows with sprinkler heads over them. Not saying you live at the airport, but there are various provisions in codes where sprinklers over windows and sometimes doors are required, typically instead of something less desirable. As long as the sprinkler can provide a water curtain over the window opening, it meets the intent of the code. It was not cheap to install, so if it was not required it would not be there. Do not move or remove that head and do not hang anything from the head or piping.