When we talk about "betting pattern", we are talking about an opponent's betting patterns. The majority of people have betting pattern. You just have to be observant to discover them. For example, some players go c-bet bigger on the flops when they have a good hand than when they are bluffing. For example, on flop, in a 10 euro pot, they will bet 7 or 8 euros when they have a good hand and 5 euros when they are bluffing. It's very important to always bet the same way. We should vary the size of our bets according to the situation and not according to the strength of our hand (unless we are against a player who never notices these details).
The betting pattern of your opponents are important
Some gamblers have betting habits that can be quickly guessed. The possible cases are unlimited. Keep your eyes open the next time you play poker. Some bluffers like to bet pot at the flop and turn and then check/fold the river. Those same bluffers might, for example, bet overbet (bet 101% of the pot size and up) when they have a good hand. By analyzing the betting pattern of your opponents, you will surely discover flaws. These pattern are valuable information for you; take notes.