"还有" (háiyǒu) is used to express "In addition…" in a conversation. It is introducing new information to the topic the speaker(s) is/are talking about. While it’s not the most challenging grammar structure, an important thing to keep in mind is that 还有 starts a completely new sentence or clause.
It’s as simple as using 还有 before the new clause or sentence. 还有 can also be used with a comma, similar to how we can say "in addition, . . ." in English.
clause 1，还有+（，）+clause 2
普通话 很难。还有 ，专家 觉得 日语、广东话、韩语，这 三 门 语言 也 很难。