This type of conflict is when the main character, called the protagonist, is enduring an internal struggle. Maybe the character doesn't know how to resolve a difficult situation, or makes certain choices that have repercussions. The protagonist could be torn between two decisions.
If the protagonist of the story is struggling against an adversary, this character is the antagonist. This could be a physical fight or maybe just an emotional conflict between two people.
When the protagonist is struggling against nature, this is an outside force he is working against. It could be a natural disaster such as a tornado or earthquake, or it could be just the weather.
When the main character struggles against his way of life or how he fits into the world this is a conflict of the character against society. This could also be a character against a law or a certain rule she is supposed to abide by, or even a child against parents or teachers.