While you are doing content, you may not understand what people are saying or telling you what to do in the party chat and this could pose a problem, especially when there’s an adamant language barrier. While not a comprehensive list, it is best to least get exposure to the words that are commonly used.

General Phrases

Be respectful in the Japanese Data Center and use phrases such as よろしくお願いします、お疲れさまでした、すみません　or どまです. In fact, with these four phrases alone, you can go a long way in being comfortable. Ilunari has provided a guide for players that are willing to break their comfort zone and learn Japanese in order to communicate.

FFXIV JP to EN Dictionary Guide - FFXIV 7.0 | AkhMorning

Relating to abilities

Relating to mechanics