In the application some values get changed in run-time, if 
you want to get those values  we will use GetToProperty.
  And at the same time if we want to set the propertiy of 
any object we will use this SetToProperty

Thanks Jyotirmai. and i have one more question that when we
will use this get visible Text property??

I hope Jyothirmai's answer is not right....

Actually GETTOProperty stands for "Get Test Object 
Property".

All the objects which are identified & stored in Object 
repository by QTP during design time are "Test Objects"

In order to retrieve the above test object's properties --- 
we will use GETTOProperty method.

seTOProperty Stands for "Set Test Object Property".
For the above test object, if we want to change the 
property values during run time(Only)...then we will use 
this "setTOProperty"

TO - means text objective properties.

1). GetToProperty --
i will one example one "OK" button is there that button 
contain some some properties i.e., 24 properties but some 
of mandatory properties are stored in to the OR. (Like 
native class, button)

If u wants to know any property of that "OK" button u can 
get this GetTOProperty method.

2). SetToProperties--
for example the "OK" button 2 mandatory properties are 
stored in OR. if u want to add one more property at Run 
Time that is temporarily. you can set the property using 
SetToProperties method.

i hope this is Right answer....
if this is wrong plz let me know...
plz mail me gi_raju@hotmail.com

GET TO property is used to get the TEXT OBJECT Property 
value of an object at the time of execution.
SET TO property is used to change the property valu of an 
object at the time of execution.