An A320 has 5 flap positions. 0, 1, 2, 3, and FULL.
Typically, 1+F or 2 and sometimes 3 is used for takeoff depending on operating factors like maneuvering speed, runway length, barometric pressure, weight, OAT, etc.
If you go for Flap 1+F on takeoff then you’d normally retract Flap to 0 at S speed (on PFD speed tape) but since the Airbus is a magical machine, if you fail to retract flap at S speed then auto retraction happens at 210 knots which means flaps are retracted and slats are still extended until you move that lever back to 0.
When in flaps 2, you’d normally choose flap 1 at F speed, then flap 0 at S speed. “O” is green dot speed as shown on the PFD speed tape as a green small dot which indicates the best lift to drag ratio speed or the engine out operating speed in clean config. Not to forget that GD speed is only displayed when in clean config (i.e. flap at 0).
Sorry if all that was overwhelming but good to know since you’re flying that machine on the simulator. Best of luck