Braggadocio is the kind of talking someone does when they are attempting to appear cocky or boastful.
It is also a synonym for braggart, which is the name for a bragger, or someone who is boastful and usually loud about it.
The plural for braggadocio is braggadocios. This is only to be used when referring to two or more people who are braggarts. It should not to be confused with the adjective form, which is braggadocious. Some confusion may come from the adjective form not being recognized by some spellcheckers, so the user would change it to the plural form, unknowingly introducing an error into the text.
Braggadocio may be pronounced with a hard or soft c, which the US preferring the soft and British English preferring the hard.