I find this particular feature of Swedish endearing, because some English speakers say the same thing, particularly in the southern US, and even more particularly in Old West movies. They say "Give me that there bottle of whiskey!" and "You want this here gun?" Priceless. :)
ser = see, att se = to see ser ut = look like, att se ut = to look like ut = out
Hence, "ser ut" changes the meaning of the two individual words, just as it does in English actually. "ser", which means "see" + "ut" which means "out" doesn't mean "see out" but "look like". Using "out" changes the meaning in English too. Look! = Take a look! For example: Look at that car! But if you were crossing the road in front of a car, someone could shout: Look out! = Careful! Watch your step! The meaning has changed.