Voiceless glottal fricative
This is a standard voiceless glottal fricative. It is also comparable to a devoiced vowel. The symbol is /h/. In Romance languages that do not pronounce this sound, and English, the letter's name is usually pronounced with a palatal or velar sound (Spanish /aʧe/, French /aʃ/, Italian /aka/, Portuguese /aga/, English /eʧ/). In Germanic languages, the name is usually pronounced /ha/.
Germanic languages
English
In all stages of English, the letter h in the initial position (in a syllable of Modern English, though most of the time /h/ comes at the beginning of a word, notable exception is behind). In Anglo-Saxon, an h after a vowel would be /x/ or /ç/ depending on the location of the vowel. The symbol h is used in many digraphs without the /h/ pronunciation, such as ch /ʧ/, th /ð/ or /θ/, rh /ɹ/, ph /f/, sh /ʃ/, wh /ʍ/, and hn /n̯/, hr /ɹ̯/, and hl /ɬ/ (the last threeare from Old and Middle English).
Other West Germanic Languages
High German, Dutch, and Low German also commonly use the symbol h to represent the sound /h/, which is also fairly common in the language.
Old Norse and Icelandic
The symbol h was/is used to mark devoiced versions of normally voiced sounds (like in Anglo-Saxon). Otherwise it is used to represent the normal /h/.
Danish, Norwegian, and Swedish
These three use the same symbol to represent this sound.
Romance Languages
Latin and Romanian
Latin and Romanian did/do have the letter h, which it was/is pronounced /h/, like most Germanic languages.
Spanish
Spanish does not naturally have the sound /h/, but in some dialects in Central and South America, the sound /h/ is used for the letter j. NOTE: This is only a few dialects, it is more standard to pronounce j as /x/ after back vowels, and /ç/ elsewhere!
French
In Normandy, which was occupied by the Norman (Viking) peoples, they brought the /h/ sound with them into Old Norman French. Even today, the Norman French language is spoken with a /h/ sound.
