This is a client-side mod. Installing it on a server won't do anything.
This mod allows you to type some emoji/symbols more easily in Minecraft. To be clear, this mod (technically) does not add any emoji to the game, it only makes typing the ones already in the game easier. For this reason, emoji typed will be visible to anyone else on a server and will still be there (on signs, books, etc) if you uninstall the mod. I can not absolutely guarantee all symbols/emoji will work on all servers, some servers have plugins that mess with chat and there is really nothing I can do about that.
To type an emoji in chat, simply type a ":" (colon), after that a list of all possible emoji keywords will appear. Once you type a keyword it will be replaced with the corresponding emoji or symbol. If you want to type an emoji outside of chat (anvil, sign, etc) the list won't appear but the keywords all still work.
In chat:
In anvil:
In book:
On sign:
