[Plugin: Jetpack 3.1.1.] Impossible to install Jetpack

hello everyone,
i started to using wp since a week, i need to install jetpack pluggin.

i tried the first time but the message was: impossible to install jetpack.zip
so i deleted some others pluggins maybe caused problems

i tried the second time to install jetpack but the message was: impossible to install because the folder already exist in htdocs/wp_cont/pluggins/jetpack_3.1.1.

so i opened htdocs with filezilla and i deleted the entire folder jetpack_3.1.1.zip

i tried the third time to install jetpack manually and this is the message: impossible to copy the file. jetpack/languages/jetpack-nb_NO.po
what does it means?

Please i need advice, thank you for every next comments.