I don't know what is mining sum friend say mining is good earning platform but sum som of friend say is not good in present time i am totally confuse.
It takes lot of time and work behind mining, it is not a get-rich-quick method. There are lots of risk that you must be willing to take, there are lot of scam trying to lure new people into cloud mining and such - stay away from those.
If you really wan't to do this, try mining some altcoins with your pc - then you ll understand whats going on.
Basically, miners are those who confirms a transaction that took place in the network, they will do this by running algorithms like SHA-256 etc.. For mining, you need to have a basic skill in handling computers and sometimes advanced skill to setup or troubleshoot.
Use this forum to do your research and get familiar with the technology (it is very interesting), then you ll know what exactly you have in hand.