>What does it mean when a developer has put this in the property of form instead of just quotes?
>

>=''
>

It depends on the property. For a property that assumes a string value (caption of a label) the = sign means evaluate the expression so

=""

is an empty string while

""

would show two double-quotes.

I know I've done it in the past, but I don't remember exactly why and I don't have the form in front of me now for a reminder.