I am newbie at bitcoin and always i saw a change in bitcoin value. What are the factors that affects the change in bitcoin value? Is it also same like real money? Like if value of Gold decreases then value of US dollar increases and vice versa.

Price fluctuations and the so called volatility.
Bitcoin is real money literally but it doesn't mean it has the same status of volatility with fiat or any assets like gold. One factor that affects the impact of fluctuations in any kinds of assets is the people's response in the market by doing buy and sell. Bitcoin traders are always on the move 24/7 actively that's why you will noticed some drastically changes every minutes or even for a seconds in bitcoin price.
Since bitcoin can quiet be manipulated or should I say, big hoarders can create a panic resulting for a big price increase or decrease, active price fluctuations is really present in bitcoin.