I've been running Princes of the Apocalypse and the PCs have gone on a little tangent involving some character backstory and the village of Beliard. The POTA book doesn't go into much detail about Beliard, I'm just wondering what the population of the village is? Maybe there's an old 2nd, 3rd or 4th edition book that talks about it?
While there may or may not be a canonical answer for the population of Beliard specifically, if you have access to the 5th ed. Dungeon Master's Guide, you can determine the general population of a settlement using the rules set forth in the chapter on world building (towards the front of the book).
That table categorizes settlements from hamlets (smallest) all the way up to metropolises (largest). If I recall correctly, the population of a village ranges from about 400 to 1000 inhabitants. The next size up would be a town, and smaller a hamlet.
The Forgotten Realms wiki also lists all known villages and includes Beliard, and defines a village there as a settlement with a population between 401 and 900 inhabitants (I am not sure what edition these numbers come from, or if the same numbers are used to define a village across the various editions of D&D).
For what it's worth, specifying that it is a village, and knowing that a village has specific qualities associated with it (availability of magic items, general pop. size, etc) should be enough for most game purposes.