Hello, I am learning English,

but I a little confused about the use of the past simple and the present perfect continuous.

I give you one example below:

I have been playing tennis.

or
I was playing tennis.

What difference do you make in the meaning between these both sentences?

Thank in advance for your replies and if it is possible can you give me some examples.

See you soon (Do not hesitate to correct my mistakes, I am just a brgginner and my grammar is very poor).