And that more often than not, the speaker already knows potential solutions and next steps, they just want you to agree that it sucks. Too often, solutions driven people try to solve venters' problems rather than simply listening to what they are.
Sometimes people are more receptive about suggested solutions after you've expressed some solidarity.
"Yeah that does suck"
"That situation happened to me, it was a pain in the ass, I tried to do X, it didn't work that well, then I tried to do Y, it seemed to work ok, if I'm in that situation again, I'll probably go with Y"
If you don't want actionable answers to a problem, save it to your personal life or therapist.
Your colleagues have a duty to behave decently towards you but they are not paid to be your emotional dumpster.
Sometimes my colleague needs to went about a project that is going bad or a person that is making their life difficult and sometimes I might do that as well. You listen and sometimes you discuss solutions but sometimes it just venting about a situation you both know is shitty.
Just don't become they guy/girl who is always negative or talking shit about people though.