How does getting a professor to write a letter of recommendation to a college of my choice help out?

I am trying to get into a competitive college as a transfer student. I am attending my second institution as the first one I didn't do to well but this one I am doing great. The college of my choice stated that they want transfer students to have a 2.5, 3.0 preferred and I do have a 3.0 but at my first institution I didn't do to well like I said. Im a bit nervous and my mom advised me to get my psych 101 professor who is an alumni of the same college that I am interested in to write me a recommendation. How would that help me or the admissions counselor in the decision making process?