Conflict is the struggle a character goes through in pursuit of a goal. It’s what makes it harder for her to accomplish a task or make a decision in the novel. It’s at the core of every scene and what has to be overcome for the character to achieve her goal. It can be both external (a plot conflict) or internal (a character arc conflict). Basically, conflict is what makes things emotionally harder for the protagonist to make choices that affect the plot of the novel. The opposition driving the entire plot of a story and presenting obstacles to the protagonist on a macro and micro level.