The Mazda transmission is the system of gears and or hydraulic that transmits mechanical power from the internal combustion engine to other internal engine parts. Normally the engine operates over a range of 600 to approximately 7000 revolution per minute (rpm), but this varies from different vehicle configurations but usually is less for diesel engines, while the wheels spins between 0 and about 2500 rpm.
If a replacement is necessary, you can always easily acquire it on various automotive stores. For your Mazda model, you can find several options of Mazda auto parts and Mazda OEM parts at leading automotive stores.