In Dungeons And Dragons, we have many 5e languages to communicate with each other. Basically, the d&d 5e backgrounds will give the best access to know the one or more extra languages whichever you want. Whenever you want to get the language, you must approach the Standard Languages Table because from this table only you can collect your Campaigns Common Language.
From the Exotic Languages Table also you can collect the secret languages which others can’t speak or understand like thieves and the tongue of druids, but you must take the GM’s consent. Some of these languages which are available in both tables have different dialects for one language. For instance, Auran, Aquan, Ignan, Elementals and Terran dialects are included in the Primordial language and some more dialects are included in the other d&d 5e languages. But the creatures can communicate and understand those different dialects in the same language.
D&D 5e Standard Languages
D&D 5e Exotic Languages
|Language|| Script||Typical Speakers|
|Deep Speech||None||Mind flayers, beholders|