How can I translate "appendices" in Italian?

\documentclass[oneside]{book}
\usepackage{appendix}
\usepackage{polyglossia}
\setmainlanguage{italian}

\begin{document}
\tableofcontents
\chapter{My first chapter}
dummy text
\chapter{My second chapter}
dummy text

\appendix
\chapter{my appendix}
\end{document}


Also, why is the page number of "Appendices" 3 and not 4? Is it possible to remove the page number shown for "Appendices" from the Toc?

The appendix package doesn't define any localized string; one has to add

\renewcommand{\appendixtocname}{<Appendices>}


to the appropriate language set; for Italian it should be

\addto\captionsitalian{%
\renewcommand{\appendixtocname}{Appendici}%
\renewcommand{\appendixpagename}{Appendici}%
}


(the same for both babel and polyglossia). This doesn't solve the problem with the page number, though.

You can actually dispense from the appendix package for this.

Just do

\makeatletter
\cleardoublepage
}
\makeatother


Full example

\documentclass[oneside]{book}
\usepackage{polyglossia}
\setmainlanguage{italian}

%\usepackage{hyperref} % use it or not as you please

\makeatletter
\cleardoublepage
}
\makeatother

\begin{document}
\tableofcontents
\chapter{My first chapter}
dummy text
\chapter{My second chapter}
dummy text

\appendix
\chapter{my appendix}
\end{document}


A possibly better version when hyperref is used:

\documentclass[oneside]{book}
\usepackage{polyglossia}
\setmainlanguage{italian}

\usepackage{hyperref}

\makeatletter
\cleardoublepage
\hypertarget{appendixstart}{}%
}%
}
\makeatother

\begin{document}
\tableofcontents
\chapter{My first chapter}
dummy text
\chapter{My second chapter}
dummy text

\appendix
\chapter{my appendix}
\end{document}