There are many types of bats, but you need to have one that is the right size and weight for you.
They come in different sizes and handle lengths.
A good guide is standing a bat upright next to you.
The top of the handle should reach the top of your thigh.
Weights of bats also vary and are measured in pounds and ounces.
Sachin Tendulkar is famous for using heavy bats, but it's a lot easier to develop the basics of batting with a much lighter bat.
A good test to see whether the weight of the bat is right for you is to swing the bat with only the top hand (left hand for a right-handed batsman).
If you can to make good straight and cross-batted strokes and a controlled backswing, then that's the weight for you.