ここ = koko = here

に = ni = grammar particle for location.

ゴミ = gomi = garbage/trash/rubbish

を = wo = o = direct object marker

捨て (すて) = sute = throw away (in -te stem form)

ない = nai = not

で = de = marker used in this grammar construction

下さい (ください) = kudasai = please.

Thus: Please don’t throw away your trash here.

Edit: responded to the wrong person. Kbin indents are hard for me to read.

Edit2: add transliteration