与你= with you
例如：I'd like to share the cake with you.我想与你分享蛋糕
于你= 给你= to you
例如：I'd like to give the cake to you.我想把蛋糕给予（于）你.
于字还有在的意思,英语中则可以翻译成为介词on,at,in
例如：we have arrived at the your shop.中的at
when will we arrive in your town.中的in
于字是中文的文言字,意思较多翻译时候应酌情而定.希望楼主满意!