I dare not rule out exceptions, but most of the time, when the referent of a pronoun is obvious from the context, you can simply omit that pronoun. In your example, obviously "it" refers to learning Cantonese. So, nothing need be added. 鍾意(to like) is pronounced zung1 ji3.

佢 keoi5 We use 佢 keoi5 to refer to He/She/It. and 係 hai6 for BE(v.). But 係 hai6 will not be added to this sentence. We add it only when we want to emphasize. Similar to the english "DO". E.g. We "do" want to eat the lunch.