No entiendo lo k m dices in English?

"No entiendo, porque..." means: I don't understand because

"No entiendo, ¿por que?" means: I don't understand, why?

(the meaning depending on if por que was one or two Words)

(to add one more meaning To Laila's answer)

"No entiendo por que!" made as a statement can mean " I do not understand why! " (disbelief)