#(x,y)# is a pair of real numbers. The meaning is:
#(x,y)# is an ordered pair of numbers belonging to #RRxxRR=RR^2#. The first pair memeber belongs to the first set #RR# and the second belongs to second #RR#. Althoug in this case is the same set #RR#. Could be in other cases #RRxxZZ# or #QQxxRR#
#(x,y)# has the meaning of an aplication from #RR# to #RR# in which to every element x, the aplication asingns the y element.
#(x,y)# has the meaning of plane's point coordinates. The first x is the horizontal coodinate (abscisa) and second is the vertical coordinate (ordenate). Both are coordinates.
#(x,y)# has the meaning of a complex number: x is the real part and y is the imaginary part: #x+yi#
#(x,y)# has the meaning of a plane's vector from origin of coordinates
etc...
You will see that meaning of #(x,y)# could be whatever of above depending of context, but if you think a little bit, all meanings are quite similar
Hope this helps
