That made me look...
Does this also mean "I support you" or is it only referring to physical position?
It's about physical position only.
Είμαι δίπλα σου=I'm by your side=I support you (so, 2 in 1)
"Σε/Σας ευχαριστώ" ;)
Handy when trying to reserve your place in a queue, while being to busy/lazy to stand in it.