I guess a most simple explanation would be such as a patient begins to talk to and treat her T negatively (and later finds out that she is treating the T as if the T were her father that she hates.) She had transferred her feelings about her father onto the T. Or the transference can be positive, in that someone in past life that you loved but ignored you, you might begin treating your T as if he/she were that person from your past... bringing the T gifts, talking about meeting IRL outside the session etc.

Counter transference is something that the T has to guard against... that would be that after you begin treating him/her like someone you want to be with more etc (as per your old love) that the T then "buys into it" and feels that that love you show is real and the T begins to respond on an emotional basis. Some patients are quite good at evoking a counter-transference in a therapist...Ts have to always be on guard, and keep their emotions in check, but can use the experience to navigate the patient through their misplaced feelings.

Did that help at all???