Can explain in more detail, how do "karma" affect our life?

I learned that "KARMA" is one of mysterious things in our lives, this is the result of our actions, attitudes, and feelings towards other. In same manner, if you did bad to others for sure something worst will happen to you and same as you did good something very good awaits you, but as mortals these things will happen during and after life. As our professor states that, if you are dishonest or corrupt man today maybe in reincarnation of your life maybe you will be a beggar or one of the hopeless man in the world. See? So, better to do good to others for sure good luck may with us.

i have a story its a relative of mine he was really majestic throughout his life and never really cared for others its due to way he was brought up(he went to work at the age of 8) but during his last days he suffered more than any person i have ever seen its was very cruel i think its karma but i still have a question, if its indeed Karma, why does it punish him so hard(all he did was never care about others) when there are many people out there destroying others life for fun

karma means what you are doing. it has direct affect in our life. If you work good and be positive, help others then you will get same but if you do bad things, harm others the same thing happened with you.you have to pay for this in this life or in next life known as recarnation