I don't know anything about the game at all. T2 T3 T4 - is this the game's difficulty? How do I unlock these difficulties? I wanted to get the required level and order several boss kills with a good drop. The drop depends on the difficulty?

There are 60 Basic levels where you get skill points. After that 300 paragon lvl where get paragon point. When you hit level 60, you unlock Pit. If you do pit10 unlock T1, pit25 T2, pit40 T3, pit55 T4. Higher T more exp, more drop

i need to hit lvl 60 to unlock those torment levels and yes its hard if ur new. but 1-60 boost is like 20 fg with torment 4 unlocked hmu if u want boost for 20fg takes 15 minutes or less