Betta fish, commonly known as the "siamese fighting fish" were bred in Siam and Malaya in the 1800s as a fighting fish, similar to cock fighting or dog fighting and much money used to change hands on the outcome.
They prefer a warm 25-30 degree tank and can be kept in a mixed tropical tank with the likes of small tetras, neons,cardinals etc.. Anything that is likely to try to nip the tales of the male Betta should be excluded.
Only ever keep one male in the tank or fighting will result but a number of females and one male is no problem.
They are a bubble nest species and if you have a tank of placid quiet fish with some floating plants, broken bits of oxygenator will suffice, you may well get them to nest and spawn, although raising the young is difficult.