I received zip containing font in .afm format. Is this some sort of source-code of a font that can be converted TTF/OTF or so? How can I actually read and use this file?
As the name implies, a .afm file contains the metrics (kerning, letterspacing, etc.) information for a font. It is a Postscript file, but is not the font itself, which would have the same name with a .pfa extension. You would need both in order to run a conversion utility. The exact nature of the files and the conversion utility you would need (.pfa and .afm are generally Linux files, ascii Postscript versions of what would be compiled to .pfb and .pfm binary on Windows, for example) depends on which platform you're on.
In any case, without the actual font outline data, the .afm file does nothing.
I did find one free utility that claims to do the conversion. Perhaps some other folks here will know of others.
If you have the Type1 files (
.pfa), you can open them in FontForge and if the
.afm files are in the same directory it will import kerning and ligature information (if any) from them, or you can do it manually using File->Merge Feature Info... dialogue. Then you can generate an OpenType font (
.otf) from it.
The .afm (font metrics) file does enable you to do your text-placement calculations, perhaps previewing with a substitute font. Text so placed would look correct when rendered using the .pfa (the real font).
This would mostly be useful with runoff-style batch formatting where the lack of a proper preview isn't strictly relevant.