The term accent can have different meanings depending on its use.
In its most common general use, accent refers to a particular set of features used in pronouncing a language, typically with an association to a particular country, region or social class. For example, the Liverpudlian accent is associated with the city of Liverpool in the UK.
Accent can also be used to refer to the concept of word stress, or the concept that within a polysyllabic word, one or more syllables will be more clearly enunciated than other syllables within the word. For example, in the word communication, the penultimate syllable carries the word stress or accent so that it is pronounced com-mu-ni-CA-tion.
An accent could also refer to a diacritic mark which is made next to a letter to indicate a change in sound. The most commonly used in English is the acute accent that can often be found on words loaned from French such as café, resumé, fiancé, etc.