I have a geological style file Biblioteca_CPRM_v2.
I guess it may be something in style fonts. Any idea?
ArcGIS marker/point symbols are typically created using symbols from installed fonts. When ArcGIS Desktop is installed it adds a number of fonts into the Windows Fonts folder (for example 73 new fonts were installed by ArcGIS 10.5 on my PC).
It looks like whoever created your new Style file used a font or fonts that you do not have installed on your PC, so ArcGIS is defaulting to a different (alphabetic) font to substitute the symbol. The markers in each symbol font are stored in the position of letters in a standard alphabetic font, which is why you are seeing what look like letters through your symbols.
To fix this you will either need to obtain and install the missing font, or modify each symbol to use a character from a different symbol font.
I have opened your Style file in Microsoft Access and have been unable to determine the name of the fonts used, so am unable to help with that. You will need to contact the style creator to obtain the font, or at least find out which font it should be using.
I found the missing font. Now it's OK!
Thanks for your help.