Yes, a "constant" in the DBPro sense is simply a text replacement before the compiler starts examining the syntax etc. It's often used as a way of identifying fixed constants to make the code more readable, so instead of littering your code with the meaningless number 23, say, you might put it in a constant
That's probably the most common use of DBPro constants but you can define a constant to be anything. For example you might do something like this when debugging code:
#constant printPosition text xP, yP, "X, Y, Z = " + str$(object position x(1),1)+", "+ str$(object position y(1),1)+", "+ str$(object position z(1),1)
make object cube 1, 100
position object 1, 20, 30, 40
do
cls
` do some clever stuff
xP = 20
yP = 20
printPosition
` do lots of clever stuff
yP = 50
printPosition
` do yet more clever stuff
loop
Admittedly in that example a function would probably be simpler but there are cases where you can get "constants" to do useful things.