Various US baby name websites give a meaning of "noblewoman" for names like Erleen, Erlene, Earline, or Earlina. The idea behind this meaning is obviously that these names should be seen as female forms of the male name Earl.
On the one hand this seems possible to me, on the other hand these baby name websites tend to be very unreliable, and do not give sources for their informations anyway.
I was not able to find other, reliable information about Erleen. With only about 1000 hits when doing a Google search this name is probably very rare, with a corresponding lack of information.