Basically you give to the players “team identificator”… it can be integer 0 or 1, enum team or im using tags: “team0” “team1”…
Then on respawn get player identificator and spawn player to correct point…
However this is a little advanced, a bit more if you creating multiplayer game… i can show you my whole setup if you want but if you dont understand basics, i recommend you to focus on basics because making multiplayer is real pain. Choosing between A or B team is only 1 of 1000 problems.