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