There are 4 major factors that cause left turning tendencys in a propeler driven aircraft.

The first is the torque reaction from the rotory motion in the aircraft engine. Think of looking at the engine in your car. when you rev the engine it twists in it's cradle. Some twist a lot some not so much depending on the condition of your engine mounts. On a plane the engine is only marginaly isolated from the airframe compaired to a car so all the opposite torque from turning the propeller clockwise(from inside the plane) goes into the airframe causing the plane to roll left, and thus turn left.

The second element of left turning tendency is the affect of the clockwise spinning slipstream from the propeller corkscrewing down the fuselage and hitting the vertical stabilizer. This effect is strongest at slow speeds when you are using high RPM settings such as Takeoffs and slow flight. This causes the plane to yaw to the left. It's the same as if you were to add left rudder.

Third is Gyroscopic precession caused by the spinning propeller. When the propeller is spinning at running speed (usualy between 500-2600 RPM on most planes)it acts just like a gyroscope. Now Gyroscopes have 2 major tendencys one is they maintain regidity in space. This is handy for gyroscopic instruments like the Attitude indicator and the Gyrocompas. The second tendency is Gyroscopic precession. Precession is the resultant action or deflection of a spinning rotor when deflecting force is applied to it's rim. What's that mean? When you put a force on a spinning gyroscope you end up with it coming out 90 degrees from where you applyed it in the direction of rotation. So in a plane if you were to pitch down quickly the propeller would be pushed from the top, the propeller would cause a force to push the plane to the left. If you pull up the opposite happens. And the same with yawing left and right. And finaly the last factor in Left turning tendency is Asymmetric Propeller Loading or P-Factor. This has to do with the fact that the propeller blades are essentialy spinning airfoils. When the aircraft is level with the air it's moving through the propeller blades have the same angle of attack and produce the same amount of thrust. But when you pitch the plane up and increase the angle of attack to the moving air the propeller blade that's on the right moving downwards ends up gennerating more lift then the blade on the left side moving upward at a lower angle of attack to the moving air. So more thrust is produced on the right side of the plane then on the left and it yaws the plane left.

Now on takeoff not all of these are factors in pushing the plane left. The biggest factor is caused by the slipstream forcing the plane to yaw left. As the plane gains speed though the slip stream straightens out and stops pushing so much on the tail. Second would be torque because it twists the plane on it's landing gear causing the left main wheel to have more weight on it so it tends to move a little slower then the right wheel and pulls the plane left, and also causing the wings to produce lateral lift as they start to become effective as speed picks up causeing a slight bank to the left. P-factor only effects you once you start rotating the plane for a climb causing you to turn and lose your alignment with the runway centerline as you climb out. and Finaly Precession ends up actualy helping with trycycle geared aircraft because when you pitch up it causes a right turning force. But in Tail draggers it causes more left turning tendency when you raise the tail on the takeoff roll.

How do you counter act Left turning tendencies? Right rudder. And depending on engine torque a little right aileron. Or in Flight Simulator you can turn down the realism settings for engine torque and p-factor because honestly, they're way off to begin with.