The word ‘can’t’ is contraction for ‘cannot.’ Combined with ‘help’ you are communicating something you are unable to control or having a hard time gaining a grasp for. This can be a physical or mental action.
Here are some examples:
“I can’t help thinking about it.“
“I can’t help shopping so much.”
“I can’t help working all the time.”
“I can’t help smiling when I see her.”
“I can’t help eating so much.”
“I can’t help loving you.”
“I can not help biting my nails when I am nervous.”
“I can not help smoking when I have been drinking.”
“I cannot help feeling so sad.”
“I cannot help remembering the things you did.“