By default, SAP does not display the infotype name. But you can change it very easily.
Go to menu System => User Profile => Own data
The select last tab called "Parameters".
Then add User Parameter = HR_DISP_INFTY_NUM to the user profile with the parameter value set = X HR (note space between X and HR)
Now if you use transaction code PA20 or PA30, you can see the infotype number next to infotype name.