PokerStars - €0.02 NL (6 max) - Holdem - 5 players
Hand converted by PokerTracker 4

BTN: 121.5 BB (VPIP: 25.00, PFR: 15.00, 3Bet Preflop: 5.26, Hands: 41)
SB: 75 BB (VPIP: 32.35, PFR: 5.88, 3Bet Preflop: 1.92, Hands: 104)
BB: 153.5 BB (VPIP: 31.61, PFR: 26.42, 3Bet Preflop: 7.58, Hands: 197)
UTG: 22 BB (VPIP: 46.43, PFR: 11.54, 3Bet Preflop: 0.00, Hands: 28)
Hero (CO): 139 BB

SB posts SB 0.5 BB, BB posts BB 1 BB

Pre Flop: (pot: 1.5 BB) Hero has A 2

fold, Hero raises to 3 BB, fold, fold, BB calls 2 BB

Flop: (6.5 BB, 2 players) 2 9 3
BB checks, Hero bets 4 BB, BB calls 4 BB

Turn: (14.5 BB, 2 players) 3
BB checks, Hero bets 7 BB, BB calls 7 BB

River: (28.5 BB, 2 players) K
BB bets 7 BB, Hero calls 7 BB,

Betting flop is okay because this hand is vulnerable and you have a lot of fold equity on a 932r board. I'd probably go smaller though. When he calls I would check back turn. Having an ace in our hand is actually bad for bluffcatching. We're hoping he floated with ace high and turned it into a bluff on the river.

I'm usually one and done in this spot. That turn card does nothing for your fold equity, and you're often already behind when villain calls on the flop, so just take the free card.

Check turn, you're just value owning yourself.

As others have said, bet on the flop is good to protect against overcard hands, but sizing should be much smaller because most of the BBs range will have missed and have very low equity on this dry board.

Once he calls on the flop villain's range is gonna have a lot of pairs like A2, A3, 98, T9, all the pocket pairs and a few overcard type hands like JT and KQ.

Turn is actually a pretty good card for you since most of BBs range doesn't improve and it actually reduces the number of pair+ type hands he could have (e.g., 33, 32s, A3). This means that the 3 is a good card to keep firing if you have a BLUFF, but here you have a pair that can win at showdown so you definitely want to try and check it down on the river and probably fold if he bets.

As played with your bet on the turn, I think it's a decent spot to bluff raise since the BBs range hasn't really improved at all and we can definitely have sets, AA, AK, KQ etc. That being said maybe A2 isn't the best hand to bluff with because you block AX that villain could be bluffing with, but also block hands like 22, 32, A3 so I'm not sure.

Overall I think fold on the river, but if you're feeling creative a bluff-raise is also ok.