1 John 2:15-16 (English Standard Version)
We fairly easily understand "desires of the flesh" as wanting something, even if not good for me. As a believer we tend to think of that as drugs, alcohol or sex but it can be as simple as wanted to eat food as a comfort, rather than to give us life. To eat 2 pieces of cake, say, just 'cuz we like it - even though it will add volume to our bodies that will accelerate our body's destruction.
And the "desire of the eyes" I believe is a lust for anything that we don't have, but seeing what someone else does have, and wanting it to be ours. This could be some one's husband/wife or house, or car, or even simply spending money.
But the Pride of Life? I think this is as personal as taking pride in your intellect, your looks, your talents that have been given or perhaps a certain power or position. This is a hard thing to overcome because if you have it, you think it is because you have right to be given special attention because of it. Your beauty or good looks can become a cause of pride, or your brains, your skill, say as an actor or a person who can effect change because of these gifts. All these things are present in people with gifts or power - and it is one of the greatest temptations to believe your gifts give you rights.
But, in truth all that we have was a gift from God, and can bring great good to the world if we don't begin to honor ourselves as being important or special, or worthy of special treatment because of them. If we seek to use what God has given us to glorify HIM.