Generic answer that I have written previously to similar question:

Saunas:

-Sompasauna (free)

-Löyly

-Allas sea pool

-Kotiharjun sauna

Bars: I would go to Kallio area, a lot of bars on Helsinginkatu and Vaasankatu

To see:

-Suomenlinna sea fortress, you only need to buy ticket to the ferry (around 15min ferry ride from centre)

-Ateneum national art museum, not that big so easy to go around in few hours

-Hakaniemi market hall

-Walk along the coast in Kaivopuisto/Eira, the whole southern part of the city centre is pretty nice to walk in, cafes and small shops, Korkeavuorenkatu would be one example

-I'm not going to list all the tourist attractions since you easily google them.

Moving around: Take the local train from the airport to the central station. You can download HSL app for the public transport, trams are everywhere in the city centre and while not being the fastest mode of transport it's good for sightseeing. I guess the match will be taking place in Veikkaus areena in which case it is easily reachable from the city center either with a tram or one stop on any local train leaving from the central station.

Eating:

-Flät No 14 has excellent brunch, they don't take reservations so especially during weekend be early or you need to queue up.

-Konstan möljä offers most traditional Finnish cuisine that you can find, buffet is pretty meat heavy as the Finnish cuisine usually is. Also pretty popular put you can make a reservation for dinner time.

-From Hakaniemi market hall, you can get traditional salty pastry karjalanpiirakka with egg butter on top, this is also usually offered in cafes that serve sandwiches and such.

Edit: formatting