The languages available to 1st-level player characters in The Hollow are:
Native language of humans, halflings, and shifters. Knowledge of Common is widespread due to human trade activity.
Common sounds like your run-of-the-mill Germanic-Norman pulp fantasy.
Originally the language of the jotuns, now the native tongue of dwarfs, goliaths, and gnomes. Archaic Jotnakveda survives in certain isolated or privileged dwarf communities and is not generally taught to outsiders. Use of the archaic forms is a status marker in dwarf and gnome communities.
Jotnakveda sounds like Old Norse.
Native language of elves and eladrin, as well as aquatic, aerial, arboreal, and nocturnal peoples of faerie. Another widespread trade language. The eladrin dialect has furnished a great deal of Common's ocean vocabulary.
Ranyatil sounds like Quenya.
Native language of the genasi, uruks (PHB half-orcs), uruk-kin, elementals, djinni, and the earthy peoples of faerie. Not easily accessible to prospective learners due to the small speaker population.
Primordial sounds like Arabic or Hebrew depending on the accent of the speaker.
Native language of dragonborn and tieflings, also spoken by dragons and fiery or warlike peoples of faerie.
Dragonish sounds a little like Russian.
Native language of devas and nightharrows (FRCS drow).
Melakhrum sounds a bit like Ancient Greek.
The Deep Speech, Supernal, and Abyssal tongues are as described in the PHB.
Native speakers start out with the accent of their home community for free. You can learn a new accent between adventures. Knowledge of a language confers the ability to perceive accents; knowledge of an area confers the ability to identify the accents spoken in that area.