The greatest takeaway from therapy for me was learning to process things that for whatever reason my brain failed to process. Also accepting that it’s not a fault of my intelligence, or lack of, that I needed therapy in the first place. The brain is an organism and sometimes it just doesn’t work right and that’s not your fault.
Also there is no magic sentence the therapist will say that you’ll have some eureka moment that fixes everything. Most of us are smart enough that we know what is bothering us and why it might even be irrational. You probably don’t need a therapist for that part. In fact, I’ve found that trying to rationalize away your mental problems by yourself is like standing in a big hole with a shovel. You can’t dig your own way out. Put the shovel down and ask for a hand to pull you out.
For an analogy, in my case think of a clogged drain. Emotions are backed up and can’t go to their final destination. Through EMDR therapy (rapid eye movement exposure therapy basically) I was able to condition the drain to unclog itself and the backed up shit was able to flow like normal. My “drain” still has a propensity to clog but now I know what to watch for and some basic steps to maintain it so I won’t need to call the plumber nearly as often. But I’ll still call the plumber every now and again to check my work.