time control otb tournament?

That isn't an easy question to answer. It will depend completely on the event and what is available in your area.

For example, most events I hold in my town are one-day G/60,d5 games. I held a two-day event in a neighboring town this last weekend which was G/90,d15, but the same event is normally G/90,+30 and with added time for cleaning, we had to modify it.

Some areas may have quicker time controls, some longer.

You should look for a chess club in your area and practice OTB before trying a tournament, tbh. 

Check local libraries. 

Still curious about how many games you play on a tournament (let’s say club level).

And what G/60, d15 and +30 indicate.

Is d15 the increment, I would expect an i? And +30 maybe 30 extra minutes after a certain amount of moves?

Nah, they're slightly different.

A delay of 30 seconds, you permanently lose time after the 30 seconds, but you never gain any time.  A +30 seconds means you gain time every turn. 

So, if you play 4 fifteen second moves, a 60d30 means your next turn you have 60 minutes. A 60+30 means you now have 61 minutes to play.

Your 5th move you take 1:30 minutes. 

When you start your 6th move, on a 60d30 you have 59d30.  With a 60+30, you would have 60:30 on the start of your 6th move.

When i go to otb tournaments, it is 30+5 or 25+5 and there are 5 rounds (in the ones i have been in)

As some have said, it varies on the event but expect the time control to be around 90 min.-ish per game. With this said, my local chess club has rated USCF "Quick" and "Blitz" events maybe once a month or so. The "Quick" games are usually 25 min with 5 sec. delay and the blitz are 5 min (no delay). 

My local club has unrated games on the days of no scheduled rated events. For the unrated, it is usually the 25 min. 5 sec. delay time control, but sometimes we'll play off-hand blitz between rounds if someone is also waiting.

Very common, but this is listed under "Quick rating" by USCF I believe.