What that usually means is monthly meetings, lots of wrangling over the budget with the Treasurer, lots of wrangling over why attendance and/or giving are not matching our targets, and so forth. There are usually some other committee / commission activities associated with it, and there's sort of an expectation that you'll show up at major events, etc., so forth. It's a lot less glamorous than it sounds, but it's an important part of parish governance.
Of course, there are times when it can be much more exciting. Or aggravating. Or life-sucking-expenditures-of-energy. On my previous stint on our vestry (4 years — 1 year filling out someone's term, then a 3-year term of my own), we went through a big building campaign, our rector leaving, our assistant rector coming out (and a substantial number of our biggest donors leaving), newspaper articles, a new rector, etc., all against the backdrop of the big gay rights struggle within the Episcopal Church. Exciting times, except when you're going to long meetings a couple of nights a week doing damage control.
I'm proud of what we did at the time, but I was pretty burned out, and after my term was over I sort of dropped back into a second tier supporting role.
Until I got asked if I wanted to run this year, that my experience would be highly valuable (esp. with the turnover), etc., so forth, with appeals to my service mentality (and, perhaps, my ego) to get me to sign on. And, honestly, I've been feeling a desire to get back into greater involvement with our parish. Good people, I like the community there and what it does, and having a structured set of duties is a way for me to participate in same.
So I did. And the elections (pro forma, since the candidates met the available slots) were held this morning, and I'm in.
I'll … let you know how it works out this time around.

Good luck!
Well, hopefully there will be a lack of existential crises in the parish, or the national church, for the next few years. 🙂
As someone who served 3 full terms, and finished an unexpired term for a person who had to step down, I say, God bless you and good luck. It’s not everyone who is willing to make a return trip. I often wondered why I did. 🙂
Thanks, @Ellie.
I did take a 9 year gap in sessions. Maybe I just forgot. 🙂
Good for you!